Not tolerating intolerance is very different than "not tolerating anything". Popper argued that it is proper and warranted to refuse to tolerate intolerance, and Rawls noted that a reasonable right to self-preservation supersedes the principle of tolerance.
Everyone advocating for suppressing others always believes they hold the ethical high ground. Sometimes they do. The problem is when they don't, those tools of suppression work just as well.
USSR:
"[We call for] painless but full liquidation of the monasteries, as chief centers of the influence of the churchmen, as nurseries of parasitism, as powerful screws in the exploiting machine of the old ruling classes."
USA:
"We will not knowingly employ a Communist ... In pursuing this policy, we are not going to be swayed by hysteria or intimidation from any source. We are frank to recognize that such a policy involves danger and risks. There is the danger of hurting innocent people. There is the risk of creating an atmosphere of fear. Creative work at its best cannot be carried on in an atmosphere of fear. We will guard against this danger, this risk, this fear."
"... We request Congress to enact legislation to assist American industry to rid itself of subversive, disloyal elements."
China:
"Although the bourgeoisie has been overthrown, it is still trying to use the old ideas, culture, customs, and habits of the exploiting classes to corrupt the masses, capture their minds, and stage a comeback."
"[Our] objective is to struggle against and crush those persons in authority who are taking the capitalist road, to criticize and repudiate the reactionary bourgeois academic
“authorities” and the ideology of the bourgeoisie and all other exploiting classes"
Had no idea the slope was this slippery. Apparently you can go from choosing to not participate at a conference because an invited speaker harbors racist views to being in support of pogroms and blacklists.
The obvious implication is that the conference was expected to enforce a blacklist.
If failing to preemptively blacklist ideologically unacceptable attendees carries with it this degree of negative response, then a preemptive Hollywood-style industry blacklist is exactly what we'll get.
It's already the case that defending someone like Moldbug carries with it the risk of being branded as supporting the popular perception of his views, which in turn means you too can be on the receiving end of mob wisdom.
Curtis Yarvin is a software engineer, so if you want to make the analogy honest, a blacklist would be a large contingent of software companies refusing to hire him under any circumstances. Dalton Trumbo wasn't pressured not to speak at conferences because of his political allegiances, he was barred from working period (and eventually jailed!). This has absolutely nothing to do with a blacklist.