The most disturbing and insidious sentiment of online mobs is claiming that the targets are "just being held accountable". Or that such people are just experiencing "consequences". I really can't express just how cold and bloodthirsty such statements seem to be. It's the perfect combination of justifying vicious behavior while also absolving themselves of responsibility.
Whenever the talk of “consequences” starts, I’m reminded of a quote: “There is freedom of speech, but I cannot guarantee freedom after speech.” —Idi Amin
1. They believe that "wage slavery" exists. That is, an employee may freely agree to employment conditions under a capitalist view, but under the liberal view, they have not freely agreed since various coercive forces exist that force them agree to the employment conditions. So if a liberal believes a "freely" agreed to job is actually not free due to coercive conditions, then a liberal should also believe that free speech is not free when coercive conditions exist that control speech.
2. The idea that any consequence of free speech is acceptable is easily countered: the consequence of you calling an insane person stupid is they kill you. Obviously no normal person would think that is acceptable. So every normal person, including those liberals with internal inconsistency in this argument, know that the argument should actually be about what consequences are warranted in response to speech.