I don’t know that I would call that fascism. I think leftist governments (which we do not have) killing right wingers (frequently actual fascists) has been an unfortunate but inevitable part of defending revolutions historically. But a right wing government killing right wingers is something else entirely.
We can more or less expect our right wing government to kill leftists, because it has always done that, continues to, and would be doing a lot more of it now if there were actually more leftists wielding any sort of power. You can about count on one hand the number of right wingers the cops have murdered for political reasons, so I’m not sure the “what if they do it to us” hypothetical is all that illuminating. Because again, they always have been doing it to us.
You might find it in poor taste, but I can understand somebody not being too broken up about the shoe being on the other foot for once. Also, if this guy was posting about shooting the “Marxist” joe Brandon, I’m pretty sure he’s exactly the type of person who would happily shoot as many actual marxists as possible given the right opportunity. So I guess I’m not all that broken up about it either.
Though i do wonder if he had dementia. In which case it is in fact somewhat sad.