Kaczynski's not a leftist tho.

He's a straight up reactionary, or at least he was when he wrote the manifesto.

Like, the "trashing leftists" in question isn't sectarian infighting or theoretical criticism it's shit like

The leftist is antagonistic to the concept of competition because, deep inside, he feels like a loser.

and

The leftist’s feelings of inferiority run so deep that he cannot tolerate any classification of some things as successful or superior and other things as failed or inferior. This also underlies the rejection by many leftists of the concept of mental illness and of the utility of IQ tests. Leftists are antagonistic to genetic explanations of human abilities or behavior because such explanations tend to make some persons appear superior or inferior to others. Leftists prefer to give society the credit or blame for an individual’s ability or lack of it. Thus if a person is “inferior” it is not his fault, but society’s, because he has not been brought up properly.