They'd generally be more disciplined and physically fit / trained for combat. As long as they're screened otherwise, it seems like a great pool to draw from -- plus it helps out veterans.
The military are well drilled in rules of engagement and waiting for fire orders. Far more so than your average bouncer or off-duty police officer. I heartily wish the police force were trained and disciplined like the military, it would remove a lot of the individual variation in responses.
That was my point. Combat training in a military environment is not what you want on most civilian "bouncer" jobs. I'd imagine, anyways.