i don't think the question here was "should I bring my friend to a milsim when he's dressed up like batman and not tell anyone, where he acts like batman in a military-styled operation?"
While it's a silly idea, i think that it could work in very specific settings. there are fun nights where you could do this. zombie games has come up a lot, and it could actually be a lot of fun. other nights where it is appropriate could be imagined as well.
Realistically, though, I don't think Batman would have much of a chance. Plus, the lack of physical contact would be an issue, and I don't much feel like getting hit by a harpoon gun, or a batarang. With proper rules, I could see this being both challenging and fun, as long as the shooters are looking to shoot each other, as well as batman. because really, he'll be able to "catch" one or two people, at most.