because no one on the right believes that he’s a vegetable.
Riiiiiiight. There are PLENTY on the right who believes it, but isn't questioning it. Just because we may not know exactly why they're covering it up doesn't mean it's not true. I believe you cited Occam's razor, and the simplest explanation is that this man is as dead as Elvis.
I quote the Doobie Brothers:
"What a fool believes, no wise man has the power to reason away."