Violence doesn't turn a good cause into a bad one, or a bad cause into a good one.
I think all of the violence that has rattled the nation in the last year has been bad, and we can denounce all of it, but denouncing the violence doesn't say anything about the cause. We can't create some sort of moral equivalence in the cause if we find some the methods equally bad.
ETA: Let me be more explicit. The BLM protests were in a good cause, but we should denounce the violence that occurred. The Capitol putsch protests were in a bad cause, and it would have been bad even if it had remained peaceful.
THe obvious further problem - much of the violence we saw from "BLM protests" fell into three categories:
1 - the destitute/very young, people happy to destroy for it's own sake or loot out of need.
2 - the police, who we saw beating veterans, knocking over the elderly, teargassing people they kettled, etc.
3 - Boogalo Boys and other assorted nationalists happy to attack whoever.
Had the insurrectionists at the Capitol been wearing black hoodies and face masks and so forth, I'd have considered the idea that they were actually Black Bloc anarchists. Instead, we got muppets snitching on themselves on social media, Dances with Karens with his goofball outfit, the desert dish from the Unite the Right rally, and so forth, all happily explaining that they were doing it because Toupee Fiasco wanted them to.
At the same time...yes, lots of people went to protest/see Orange Badman without any violence at all. I won't say I'm fine with it, he was a terrible excuse for a president, but I'm fine with their behavior.