Political violence is always wrong and should never be tolerated from anyone. Once "protesters" threaten lives and property, their grievances and ideology should become absolutely irrelevant to the situation.
That is, obviously, not the country we live in.
Long ago, we had an attitude of zero tolerance for terrorism, "we do not negotiate with terrorists," etc. One reason for this was the implicit understanding that negotiating with terrorism legitimizes it. Violence becomes an instrument of politics.
Some of us warned all last year that treating violence as acceptable, even laudable, from SOME people would mainstream it and touch off an arms race. Everyone would start getting the idea that only groups with a demonstrated capacity for violence are taken seriously.
When violence becomes acceptable from one party and its clients, one ideology, it becomes an instrument of authoritarianism. That's why authoritarian regimes frequently have violent vigilante groups roaming the streets in addition to their vast security and military forces.
Iran, for example, has all sorts of heavily armed police and security forces, working for both its secular and theocratic governments, but it ALSO has ultra-violent "vigilante" groups indulged by the State whose "grievances" supposedly justify vandalism and murder.