I think Perelman himself wouldn't care too much what you call him. He would say something like:
“Everybody understood that if the proof is correct then no other recognition is needed.”
(As he said before.)
You don't need a license to be a mathematician. There's this conjecture, undecided for 100 years. Whoever solves it gets the glory. He doesn't have to be a "mathematician" or an "expert". A correct proof is all it takes.
He solved it, and all that's left for us is to discuss whether he's an expert or not:)
Another reason for turning it by 45 degrees is backward compatibility. If you play a stereo disc on a mono player you want to get a "mix" of the channels instead of one of the channels.
You don't need a license to be a mathematician. There's this conjecture, undecided for 100 years. Whoever solves it gets the glory. He doesn't have to be a "mathematician" or an "expert". A correct proof is all it takes.
He solved it, and all that's left for us is to discuss whether he's an expert or not:)