I think someone here established that these weren't LEOs, but private security guards. It's a moot issue for the OP's problem.
However, if it were a situation where an LEO is in department uniform, it doesn't matter if he's on-duty and assigned to an event or if he is authorized to wear his uniform while moonlighting. If he is in uniform, he is acting as an agent of that department.
Most, if not all, departments (mine included) that allow you to moonlight in uniform under certain circumstances make it clear that you are held to the same policies, rules, etc. that you would be if working your regular duty assignment. And a complaint on an officer moonlighting (or just plain off-duty) would be handled the same way it would be if it was from an on-duty event. On-duty or off-duty or anywhere in between doesn't matter.
If my wife thinks I have a girlfriend on the side and notifies my agency, they'll open an "ethics investigation". I've never seen it happen at my agency, but I've heard of Shelby County deputies getting suspended for ethics violations for infidelity. Don't know it for fact, though.