As well-meaning as their intentions are (excluding the ones who are doing this for clout obviously), I can't help but think that all it will do is add to the confusion of an already hostile situation, if not make them a liability as well. The Americans who are still over there, soldier and civilian alike, are cut off from almost all forms of immediate support and reinforcements. A handful of extra Americans, both eager veterans and "weekend warrior BRCC dude bros" alike, will likely find themselves in the same helpless situation as everybody else. Angry Cops, a YouTuber who makes comedy-oriented content on military affairs, made a quick video highlighting what should not be done during an active shooter incident a few years ago:
Dan Blizerian made an interesting choice during the Las Vegas Shooting
www.youtube.com
Now imagine the confusion being that much more expansive, as well as dangerous, in what is practically a warzone.