1. I'm not automatically assuming that every white person is MAGA. But let's go through some things:
Most white men are MAGA. That % increases when you add guns to the mix. In addition, this sounds like stochastic terrorism, which we know is a right-wing thing. And it just happened to start on the day before the election, when people were predicting and worried about violence.
On the flip side, he's in college. But it's not Chapel Hill; it's state.
So if you evaluate those factors, I'd say that it's considerably higher than 50% chance that he's a right winger. That's less than 100% but I say more probable than not. Additional information can, of course, bring those odds down considerably.
Mental illness is another possibility, as mentioned. And even if it's not mental illness, it doesn't have to be politics.
2. His conduct happens to be what the FBI, DOJ and terrorism experts were predicting what would happen. So put all those together and it's not a stretch at all to think that he's MAGA.
3. It is possible that all of the above can be true and he's a liberal who lost it. That wouldn't make me any more sympathetic to him. I just think it's considerably less likely than the alternative.