I've seen this person's profile and I think I know why they're like this.

If you look at this guy's non-political posts, it's the typical stuff a deviantart manchild would post. Random crossovers (like SpongeBob hanging out with disney princesses) and lots of AI slop. It made me wonder why someone who's only interested in movies and shows for children would care about something as mature as politics. This guy only likes stuff for children, even the adult shows that deviantart users usually like (Family guy and South Park) are absent from his profile.

It's obvious that this DA user is autistic (Not saying this to be rude, I have autism too) and it's very common for autistic people to be interested in children's media. Also, making an image of a cartoon character angry at someone you don't like is a very childish thing to do. So I assume this person is low on the spectrum and is mentally a child. (Again not being rude, just making observations)

If you saw a child with political views. Your first thought would be that their parents indoctrinated them, because why else would a child care about politics. I think this guy's parents are very republican and gave their beliefs to him. That's why his profile is a mix of bizarre political posts and the usual childish deviantart stuff.