The only thing to remember is that there are already plenty of people out there who eitehr want to run him down or catch him running down someone else on his team, whether it's Marshall or the Offensive Line or the Coaching Staff or the Ownership, so he has to only go so far, even if there's something he feels strongly about.
Manning last year of course made big news when he called himself an "elite quarterback" or something like that. His team spent half the year getting asked about it, until he sorta went out and had an elite season and won another Super Bowl. So if he talks big and backs it up, great. If he goes after someone, the press will be thrilled to keep blowing that up until it becomes a serious team problem.
That's where skilled media coaching comes in. Making sure a guy knows what the limits ought to be before he gets on the air.