Probably because the trainer originally just said she was mooned. A story everyone agrees with and Manning never denied. However, everytime the trainer brings this up, she adds another twist to the story to get more attention/money again. Now that she is accusing him of rubbing every private part a man has on her face while she was powerless to stop it, I imagine he would now feel the need to stand up and remind people of the original story she brought up. His word was never relevant before now. Considering her original complaint was seeing a butt in the men's training room.