I dunno...
I read Hugh Schonfeld's "The Passover Plot" when I was in high school, and I was very sympathetic to it's main thesis. No one really knows what actually happened back then, of course, we are rather short of data; but Schonfeld's thesis fits the facts just as well, if not better, as the conventional story.
I would remove this item from the conspiracy list and move it to somewhere between "unproven, but not impossible" and "likely, but not certain". Dr. Schonfeld, BTW, was not a crackpot. He was a Jewish Biblical scholar. He may be mistaken, but he's not crazy.