Stop and frisk isn't "seek out black people", they found the person first and then identified him as black and that means he is a risk and needs to be stopped and frisked.
I didn't interpret the article as "investigate LARPers to make sure they're not domestic terrorists" so I don't really understand your take. Stop and Frisk has obvious racist origins, but the process starts with you suspecting someone of a crime and using that as a foot in the door. This seems the opposite guidance of "before you spend too much time investigating a group, try to build the case that they're not LARPing". Like the whole preface is that terrorists are trying to evade justice by saying it was all a game. Stop and Frisk wasn't created because people carrying weapons and committing crimes were pretending to be minorities so cops wouldn't be suspicious.