I remember playing one of the early CS betas as a Half-life mod in ~1999. It was such a huge leap in gameplay and style from anything else out there. Most FPSs up to this point were SciFi based, guns like the BFG and plasma guns. Counterstrike's focus on realism really altered how you connected with the game. Columbine had happened very recently and was still very much in the zeitgeist. There was a very real cultural…
We knew that this would be interpreted as threatening by the powers-that-be at highschool These days that kind of behavior, if reported to law enforcement (mandatory reporting in some cases), will get investigated with the potential for criminal charges, and likely school expulsion.
Without a clear expression of threat, I don't think simple mapmaking is sufficient grounds for a terror threat charge.