I've never heard of that rule. I've certainly cleared DFW security more than 2 hours before the flight (though probably not 4 hours). Lots of folks arrive early these days, and other folks may have very long connections and decide to step outside security for a smoke.

In any case, DFW has something like 15+ security checkpoints. Even if one does deny you, the next one probably will let you in.

Absolute worst case, you could probably find the game on TV in a bar in the Hyatt, connected to terminal D, landside.