My brother went to the range last night and was pestered to death by an anti-gunner

My brother was born with a genetic condition that causes him to have a disability. He went to the range last night with his suppressor. He notices a guy looking at it weird and the guy asks him if he's a "silencer" enthusiast. My brother just tells the guy that the ATF calls them suppressors. The guy loses his mind about how they're called silencers not suppressors and my brother tells him again that the ATF calls them suppressors. The guy proceeds to say how they're not practical for everyday use, my brother tells him that he got it for helping with his hearing loss from a different accident. The guy says that he's sorry about that and leaves. My brother is shooting for a while and notices that same guy is looking over at him every minute or so. The guy starts moving closer and closer to where my brother is shooting. My brother asks him if he needs help with his guns and the guy again loses his mind about how this is a "war machine" not a gun, my brother tells him again that the ATF calls them guns. My brother starts to pack up and leave, and the guy starts begging him to stay and say he's sorry again. My brother says that he's sorry for his hearing loss but doesn't accept his apology.