There are simply things you don't say when you're part of a team, and that's one of them.
I don't necessarily blame him for doing an "Ole!" job for that pass, since he would have gotten clocked pretty hard. It's the fact that he said what he said, that painted him into that corner. You just don't do that.
Had he simply kept his mouth shut, the boo birds would have quickly quieted down, but instead, he cemented his legacy as a toxic player.
On another note, Charlie Garner was a class act, both in Philly and San Fran. If anything, he did a fantastic job at San Fran in the late 90's, when those teams weren't quite as talented as the ones that Watters played for while he was there, since they were still paying for all of that massive overspending during that Superbowl run.