There's absolutely a reason not to show it on camera. There's a world of difference between suggesting it and showing it outright, which would change the movie, change the rating, etc etc etc. If that was the case,why wouldn't every single movie have blunt, penetrative sex in it?
But beyond that, I was simply telling the other user that's what was reported, and that's what Robert himself said. I couldn't be sure he'd heard that information. I can't prove it was true, just like nobody here can prove it isn't.