You don't have to give a shit. I don't care in the sense that I don't go to NFL games or even watch much on TV. As to why they should be treated different than you regarding carry, they have a legal obligation to intervene if they witness a crime and they can be targeted by any number of dirt balls they have arrested. I think probably the only guys you have to worry about are few jealous husbands and boyfriends. And if you were careful, they are smaller than you or big wimps.
Maybe I'm being a bit naive, but I would figure that such a large public event, like an NFL game, would have an extensive series of pre-planned responses to deal with the full spectrum of threats. While you may not see the LEO at a game, I'd be very surprised to learn that LEO would have a minimal footprint at such a potential target.
The public ownership of stadiums was a caveat that had me curious, but the NFL is big enough that they can set their own rules and expect a city to fall in step.
It is an interesting decision and I'd be curious as to what prompted the change.