Honestly, I'm kind of surprised there isn't some sort of contractual mechanism for these guys preventing them from participating in those kinds of off season activities. This IS the pros now basically, and they have that kind of verbage written into their contracts.
I realize trying to prevent college kids from doing wild and reckless stuff is like trying to herd a pack of greased up cats, and that these guys aren't under employment contracts because of the semantics of them not being employed, but still, I can absolutely see a day coming when this comes to pass.