Well that’s why CCW training tells you to put your gun away if you’re sure it’s now a safe area, and if it isn’t now a safe area (possible other shooters for instance) to GTFO and call the cops and your lawyer. Also why you should give a description of the active shooter if you call it in, so they know “oh this dude in a T shirt may be a defender, we recieved a call about a guy in tac gear.” Of course, most often the shooters specifically target gun free zones because you can’t have one there, so you technically likely shouldn’t have one anyway, so makes sense the cops wouldn’t expect a defender in those cases either.
Yeah it’s something that everyone needs to decide for themselves (my issue is when people like to decide things for others.) It definitely can be helpful in a specific scenario, like a hammer to a nail, but it is also a responsibility and if you aren’t able or willing to, you shouldn’t, that simple. Especially if as you say you are you’re priviledged enough to live in a good area, in contrast to pizza delivery drivers (well, “ex”) who live in bad neighborhoods who may need them.