Sure thing. The Helldivers games use sequences of arrow keys to activate special abilities called Call Ins. That particular sequence is really well known to anyone who plays the games, because it activates a very popular call in that drops a 500kg bomb on your target. It's an ability you use when you want something really, really dead.

Of course more recent reporting seems to suggest that this guy was actually a Nazi, and that he killed Charlie for not being fascist enough, but fuck it, Charlie Kirk is dead either way. If it inspired a bunch of dickwad right wingers to hurt themselves in their confusion, that's a win for Helldivers IMO.