While a great sinner (at times), David is presented as one of the most compassionate, empathetic, and kind people in the Bible. I am sure that this was one of the secrets to his great leadership as well. Note the following examples:
- David deeply mourned his own mistakes and mistakes as recorded in Ps 6, 32, 38, 51, 102, 130, 143, etc.
- David's compassion even extended to his enemies, most notably, King Saul whose suicide was genuinely mourned by David, 2 Sam 1:11, 12, 17-27.
- David's kindness to Mephibosheth, 2 Sam 9
- David's compassionate and just anger at Joab's murder of Abner (David's enemy), 2 Sam 3:31-39
- David's compassionate and just anger at Ish-bosheth's murder, 2 Sam 4.
Thus, it is entirely credible that the very empathetic David would have been willing to die in the place of his beloved but still stupid son, Absalom, as per 2 Sam 18:33.
However, I am also convinced that David's feelings of love for his rebellions son was compounded with the acute knowledge that David was partly responsible as Elliott observes:
(33) Was much moved.—David’s grief was not merely that of a father for
his first-born son, but for that son slain in the very act of
outrageous sin. His sorrow, too, may have gained poignancy from the
thought—which must often have come to him during the progress of this
rebellion—that all this sin and wrong took its occasion from his own
great sin. Yet David was criminally weak at this crisis in allowing
the feelings of the father completely to outweigh the duties of the
monarch.
The Cambridge Commentary expresses this even more pointedly:
- was much moved] Better perhaps, was sore troubled. Sept. ἐταράχθη is a good rendering. This passionate outburst of grief was due not
only to the tenderness of affection, which was so striking a trait in
David’s character, but to the bitterness of the thought that the
rebel, the would-be parricide, was thus
“Cut off even in the blossoms of his sin,
No reckoning made, but sent to his account
With all his imperfections on his head;”
and that this terrible catastrophe was the fruit and the punishment of
his own crimes. The heart-broken cry “Would God I had died for thee”
was not only the utterance of self-sacrificing love, but the
confession that he had himself deserved the punishment which fell upon
another. Cp. ch. 2 Samuel 24:17.