Hmmm... comes close to lynching a ton of people, if you ask me. Never mind who´s right or wrong, the point is that we all agree upon trusting a judicial system to do this kind of thing, don´t we?
Depending on what the user posted, they might be embarrassed, lose their jobs, or end up in court.
We can have a reasonable discussion about the ethics of hacking a site like parler, but not if the starting point is "this is the equivalent of violent mobs literally murdering innocent people".
Of course, 99% of that is meaningless bluster but 99% of the crap on Parler was also meaningless bluster.
So I think it remains an open question as to what the consequences of this hack will be. I don't think it's impossible that someone may be literally murdered.
But if it happens I'm sure everyone in the causal chain will be as quick to claim no responsibility as the Parler CEO was...