I hate to be "that kind" of leftist but political violence has always been normalized and accepted. Cops exist to uphold the law, the law is made by politicians, cops use violence to uphold it.
"Oooh but [person being beaten by cops] did something illegal" yeah. We decided it was illegal and we decided violence was fine to use to keep it that way. I'm not saying it's good or bad or I disagree or agree or whatever, it's just how it is.
Saying you're for political violence is just being honest. Everybody is for it, they're just against violence that influences them negatively.
I agree with all of that, but I think what's relevant here is that more people are becoming willing to aim the violence in the other direction, from the masses and towards the state. You are 100% right that political violence has always been normalized and accepted, but specifically (like in your example) it was the state use of violence against people that was normalized and accepted while people using violence against the state was broadly considered not just taboo but immoral.
The numbers in OP aren't just describing an increase in acceptance of all "political violence," but an acceptance for the masses to wield that political violence against the state, which is a very interesting, maybe even profound shift, a shift that is indicative of the ongoing collapse of the empire.