The Book of Judges relates a story of the founding of a northern settlement by the tribe of Dan, in which the Danites conquer a defenseless town and set up an idolatrous shrine there. The priest at this altar is a a young Levite named Jonathan, identified by most translators as the grandson of Moses, but sometimes as the grandson of Manasseh. The latter is supported by a literal reading of the text:
a scribal oddity... presents the name of Manasseh as מנשה, with the "נ" superscripted, which does not occur elsewhere in the Bible; the correct reading may be Moses (Hebrew: משה, Moshe), and Rashi and other sages suspected as much, arguing that the name was changed to Manasseh to avoid scandalising Moses.
Whether based on this explanation or not, most translators agree that Jonathan's father was Gershom the son of Moses.
Various ideas have been put forth regarding who this Gershom really was. A novel theory is proposed in a scholarly article by Josiah Derby in the Jewish Bible Quarterly. He first summarizes the arguments for the historicity of "son of Manasseh" and "son of Moses" and dismisses them both. His conclusion, however, is that "son of Moses" is the correct reading, but it is not historical. Instead it is a fiction created during the reign of Jeroboam I to give legitimacy to the shrine at Dan. (Not that Jeroboam would agree that the shine was idolatrous, only that it was founded by a grandson of Moses).
By associating the sanctuary at Dan with Moses, he [Jeroboam] hoped that it would acquire a sufficient degree of sanctity to lure the people away from Jerusalem. These two cities [Dan and Bethel] could compete with Jerusalem for the religious loyalty of the people because at that early stage in the history of Jerusalem as an Israelite city it had not yet attained the holiness it acquired in the course of time.
Given these and any other data available, who really was Jonathan, grandson of Moses (or Manasseh) identified in Judges 18 as the father of the founder the Israelite shrine at Dan?