I read an article on this & the comment by the head coach is that "John wouldn't do this". If you remember when he was tested before the Cormier rematch the first time, he tested positive for banned substances & claimed it was a sexual enhancing drug that made him test positive. This is just another desperate attempt to save his own ass. That's my opinion at least.
If he can prove he didn't do it, than ok. I would say that is highly unlikely though. I hate to say it, but I know several guys that have got in trouble pretty much there whole life & when they get caught, it's the same thing every time... "I swear I didn't do it!"