From their perspective, all states (especially western liberal states) use violence to enforce their capitalistic order. “Authority” is broadly interpreted as ubiquitous, and all successful revolutions have been to some degree violent.
Not to suggest all authority and violence is the same, but to them, the liberal apprehension to utilize violence is a self-imposed handicap that not even their opposition undertakes.
Similar to leftists frustration with establishment Democrats from using their majority to enact progressive reform.
To them, the only distinction left is the economic structuring that violence is utilized on behalf of.
Again, not my personal position, but this “auth communists are the same as right wing authoritarians” is just willfully ignorant.