It's not necessarily a threat of violence. A lot of people would just feel ashamed to criticise other people in person would feel fine to do it on the Internet. Being a dick is a lot harder when you can see the effects of your words on the other person.
Tbf, a threat of violence is only one way to read his response (I know nothing about this Paul dude and his personality, so maybe it was 100% a threat idk).
I could also see his comment as meaning "just because you're behind a computer screen doesn't mean you should feel able to say shit that you'd never say to a person's face", because let's be honest, that's a reminder a lot of folks on the internet could use, regardless of who could kick whose ass
Maybe he's just pointing out it's rude to say and asking if this guy would behave this way in person. Notice he didn't bring violence into the conversation, the other guy did.
Very respectable honesty. Unlike the dude I saw the other day who got his ass hass handed to him by the Israeli UFC fighter. It was actually very funny.
How many times do you imagine them giving as good as they get?
Fascists live in a simplistic fantasy world of grievance, hierarchy, and spite, and it's practically a law of the breed that they don't think to the step after "I punch them."
This is, to my mind, the most telling quote of World War II that largely sums up why the fascists thought they'd win it:
"The Nazis entered this war under the rather childish delusion that they were going to bomb everyone else and no one was going to bomb them."
-Marshall Arthur "Bomber" Harris
They do not think to the next step, the actual fight between two people. They just jump in their imagination straight to their "inevitable" victory. It's probably a large part of why they're fascists in the first place.
If he wants to go to jail that is his right for proving something we both know he's capable of. But normal people should be able to take feedback or criticism without violence