It's not hard to believe. They banned the standard piledriver maneuver after Owen nearly paralyzed Austin with a botched variation of it (still effectively shortening the career of one of their biggest superstars of all time), which is why you never see anyone use it anymore outside of a few rare exceptions (namely Undertaker's Tombstone Piledriver, simply because the move is so iconic as his finisher.) When Punk busted out the piledriver on Cena during their Raw match in February of 2013, Vince reportedly blew a gasket over it and they even edited out the move on replays of the match. Not hard to buy they might have done the same with the Styles Clash if they think the move is too dangerous (then again, the same could be said about a lot of other moves as well, but WWE banning certain moves because of the potential risk and not others is just the usual inconsistency on their part.)