It's not simple mapmaking though is it? It's creating a map inside a video game to simulate school grounds.
Drawing a map of the school and putting it in a frame on your wall? Fine.
Drawing a map, recreating it inside a first person shooter, then spending hours playing (training) memorizing the map? I believe anyone could see that as a terroristic threat.
Edit: Example Legos. Having a Lego model of the US Capital? Fine
Have a Lego Capital, attend the Jan 6 protest, have books and other militia type information? Probably going to get questioned by the feds.
https://www.businessinsider.com/fbi-took-lego-set-of-capitol...