Somebody died in that crash. There’s been literally hundreds of books and movies on how to fake your own death, plane crash has been the chosen method in many of them.

I wouldn’t be surprised if he’s alive, but I don’t base my (Q) belief system on it.

AFAIR Q said Jr is dead.

Edit: what I mean is that NTSB doesn’t need to be in on it. Somebody was made to resemble Jr, and he was in the manifesto, hence NTSB was made to believe he was on that flight, and (wrongly)made that conclusion.