My own conspiracy theory is that he's being "got at" because he's had the temerity to wander off the leftist plantation (he's a registered Democrat and donor to Democrats). In particular he wrote a book The Case Against Impeaching Trump, and has supported due process for Trump as well as for the targets of #MeToo allegations. (The Left no longer likes due process — mainly the presumption of innocence — because it gets in the way of "believe the victim" and stopping the likes of a Kavanaugh appointment to the SCOTUS).
So this is a kind of taste of leftist medicine for Dershowitz. Take that, you rotter! Take that, you traitor! You traitor to the cause! You sexual predator! From a vengeful Left.
At least that's my theory, which is mine.
ForDershowitz 's final para:
In more than half a century of litigating criminal cases, I have never seen one in which the evidence of innocence is so incontrovertible and the evidence of guilt nonexistent. If my evidence is "inconclusive", then no falsely accused person can ever clear his name.
I Want to Be Investigated by the FBI