Well, there's only one way to find out.
But I fully admit, it's only just a gut feeling of mine that the coach is trying to enforce an "anti thug" policy, and not really an "anti gun" one.
If he finds out some other kid on his team is bragging about a hunting trip with his family, or his USPSA/IDPA standings, I'd bet the most he'd do is tell the kid to shut up so the coach does not have to deal with questions regarding the "double standard" he was enforcing.
I don't support the coach's blanket statement, but as a football coach who has concerns that some of his team will wind up as front page news for the Glock Forty in their waistband at some club, I can undersand the rationale. And I can understand not knowing a good way of announcing an "Absolutely No Guns,
unless you're a responsible gun owner who, hunts, shoots competitively, belongs to the NRA, or a gun-range etc.."-policy