I mean, it was violence for the purpose of promoting a social/political view...which is terrorism.
Whether or not it is justified given our current circumstances, or the fact that the government is going to weaponize the law as much as they can against him are separate issues.
It can be a real uncomfortable discussion if/when terrorism is justified when all other avenues of peaceful change have failed, but it is what it is.
Edit: apparently a lot of people think it only counts as terrorism when you disagree with it.
Terrorism specifically has a negative connotation with it. You could just as easily call him a revolutionary. The only difference between "revolutionary" and "terrorist' is whether you like the guy.
Again, we seem to be agreeing. But if his motives were based on promoting his political beliefs, whether or not they're correct, whether or not the actions are justified and for the greater good, and regardless of how the government defines it, it's terrorism. You correctly point out that he could also be called a revolutionary as the difference is largely whether or not you agree with him...but that doesn't change the fact that it's still a form of terrorism and people are getting upset that he is being charged with terrorism....which it is, and you would expect the government to use the word with the negative connotation here.
What social view was he attempting to promote? Afaik, he was exacting revenge against the person he felt was most responsible for his and other people's suffering. That's not terrorism, that's murder. Had he issued ultimatums, and published his manifesto, then maybe it would be terrorism.
It seems to be the same social views we are all talking about now regarding for profit health insurance being a parasite on our nation. He left messages at the scene on bullet casings referencing a book criticizing the health care industry, and from what I read he didn't even have UnitedHealth insurance. I recall the early reporting after his arrest including a note referencing how it had to be done and he was the first.
If it turns out he really was just disgruntled and just wanted to kill a CEO for purely personal reasons, then yeah, not terrorism. But I feel like you don't leave clues and messages without hoping to be the first of many.