Most relevant hermeneutical conclusion: "super apostle"
This is a question about multiple Bible passages and/or claims about the Bible from a single sermon with a single point. So, we need multiple hermeneutical studies, which could be separate Answers, but are in one Answer to address the one sermon they appeared in. Here, we are not developing theology because the verses are not synergistically combined to create an additional doctrine.
1. All through Church history, Jesus's return was immanent
This NT mindset is good to know when interpreting Bible passages.
But, neither NT apostles nor church councils ever predicted a date!
Paul thought Jesus would return in his lifetime. This is not an old teaching in the church. Many sermons and theologies use these verses to support this:
1 Thess 4:17 (NASB)
Then we who are alive and remain will be caught up together with them in the clouds to meet the Lord in the air, and so we shall always be with the Lord.
2 Thess 2:2 (NASB)
that you not be quickly shaken from your composure or be disturbed either by a spirit or a message or a letter as if from us, to the effect that the day of the Lord has come.
...That is from Paul. His understanding suggests it could happen at any time.
From Jesus, this is what the NT community was expecting immanently, nothing here suggests the timing...
Mk 13:24-26 (NASB)
24 “But in those days, after that tribulation, the sun will be darkened and the moon will not give its light, 25 and the stars will be falling from heaven, and the powers that are in the heavens will be shaken. 26 Then they will see the Son of Man coming in clouds with great power and glory.
Mt 24:29 (NASB)
“But immediately after the tribulation of those days the sun will be darkened, and the moon will not give its light, and the stars will fall from the sky, and the powers of the heavens will be shaken.
Jesus taught against predicting dates, even he wouldn't do it
...The NT community wouldn't have guessed the timing because Jesus explicitly taught—and Matthew reported and believed—that timing is not even known to Jesus...
Mt 24:36 (NASB)
But of that day and hour no one knows, not even the angels of heaven, nor the Son, but the Father alone.
So, NT apostles belief that Jesus's return was immanent with unspecified time is not precedent for being errant about Jesus returning at a specific time. The exegetical error from this teacher is not that his predicted date was wrong, but that he predicted a date when Jesus instructed us not to. He was already wrong before the date passed and no more wrong after it did.
2. Peter didn't claim the sixth seal was open
But, there are other hermeneutical blunders in this quote. Consider this statement from the OP's quote in quesiton:
Acts 2:16-17 Peter declared that the 6th seal was opened.
No, he didn't.
Acts 2:16-17 (NASB)
16 but this is what was spoken of through the prophet Joel:
17 ‘And it shall be in the last days,’ God says,
‘That I will pour forth of My Spirit on all mankind;
And your sons and your daughters shall prophesy,
And your young men shall see visions,
And your old men shall dream dreams;
Peter said this to explain the question many people in the crowd had from just a few verses before...
Acts 2:5-7 (NASB)
5 Now there were Jews living in Jerusalem, devout men from every nation under heaven. 6 And when this sound occurred, the crowd came together, and were bewildered because each one of them was hearing them speak in his own language. 7 They were amazed and astonished, saying, “Why, are not all these who are speaking Galileans?
There is nothing there about the seals from Peter. There is no question about the end of the times, nor is anyone asking about the stars disappearing or the moon going berserk. Nor, is the sixth seal of Revelation related to anything from Acts 2:5-17 nor Joel 2:28-29 that Peter refers to.
Sorry for the copy pasta, but look and see for yourself...
Rev 6:12-17 (NASB)
12 I looked when He broke the sixth seal, and there was a great earthquake; and the sun became black as sackcloth made of hair, and the whole moon became like blood; 13 and the stars of the sky fell to the earth, as a fig tree casts its unripe figs when shaken by a great wind. 14 The sky was split apart like a scroll when it is rolled up, and every mountain and island were moved out of their places. 15 Then the kings of the earth and the great men and the commanders and the rich and the strong and every slave and free man hid themselves in the caves and among the rocks of the mountains; 16 and they *said to the mountains and to the rocks, “Fall on us and hide us from the presence of Him who sits on the throne, and from the wrath of the Lamb; 17 for the great day of their wrath has come, and who is able to stand?”
Now, in Joel 2:30, Joel starts talking about the events of the seals, also Mark 13:24-26 and Matthew 24:29. But, that's not what Peter quotes. Peter only claims that the "spirit poured out" part happened (Joel 2:28-29). The rest is from Joel, but not a part of Peter's claim...
Joel 2:28-32 (NASB)
28 “It will come about after this
That I will pour out My Spirit on all mankind;
And your sons and daughters will prophesy, Your old men will dream
dreams,
Your young men will see visions.
29 “Even on the male and female servants
I will pour out My Spirit in those days.
30 “I will display wonders in the sky and on the earth,
Blood, fire and columns of smoke.
31 “The sun will be turned into darkness
And the moon into blood
Before the great and awesome day of the Lord comes.
32 “And it will come about that whoever calls on the name of the Lord
Will be delivered;
For on Mount Zion and in Jerusalem
There will be those who escape,
As the Lord has said,
Even among the survivors whom the Lord calls.
This looks more like what Jesus describe in Mark 13 & Matthew 24 (above).
3. This is really about false apostles known by their eisegesis
There are Bible passages that this exemplifies. Perhaps to ask this Question Jeopardy style, the title could be rephrased, "What is a super-apostle: two examples of eisegesis"
Related is a Question I had to close, but it could re-open. What all do we know about people by their fruit? In this situation, the fruit is inverted hermenuetics from someone claiming to be an apostle.
The problem with this Bible teaching in the OP quote is that it presents an argument demeaning the accurate beliefs of NT apostles as a means of defending the teacher's own credibility. Though nice-sounding, those conclusions don't mix.
Paul also dealt with so-called "super apostles":
2 Cor 11:5 (emphasis added)
(CEV)
I think I am as good as any of those super apostles.
(CEB)
I don’t consider myself as second-rate in any way compared to the “super-apostles.”
(ESV)
Indeed, I consider that I am not in the least inferior to these super-apostles.
Teachings in the name of Jesus that went against the teaching of Jesus was indeed a problem in Paul's day.
Gal 1:9 (NASB)
As we have said before, so I say again now, if any man is preaching to you a gospel contrary to what you received, he is to be accursed!
It seems that this problem hasn't gone away. And, it is arguably an indication of the end approaching. Paul thought increased false teaching would also indicate the approaching end...
2 Tim 4:3 (NASB)
For the time will come when they will not endure sound doctrine; but wanting to have their ears tickled, they will accumulate for themselves teachers in accordance to their own desires,
But, Jesus said it would get far worse, even before the events of the sixth seal he describes in Mark 13 and Matthew 24.
Mt 24:5 (NASB)
For many will come in My name, saying, ‘I am the Christ,’ and will mislead many.
We haven't quite gotten to that point, but we're getting there. This teacher indeed demonstrates that we are closer to Christ's return, but, Biblically speaking, not for the reasons presented.
2 Pt 2:1-3 (NASB)
1But false prophets also arose among the people, just as there will also be false teachers among you, who will secretly introduce destructive heresies, even denying the Master who bought them, bringing swift destruction upon themselves. 2 Many will follow their sensuality, and because of them the way of the truth will be maligned; 3 and in their greed they will exploit you with false words; their judgment from long ago is not idle, and their destruction is not asleep.
I think you were right to raise questions. This is not about the credibility of NT testament apostles, but about identifying so-called "super-apostles", both in the day of the NT apostles and predicted to be in our day also.