The classic cult tell is the fact that if you strip out all the claims to spiritual and moral wisdom, cults exist to service the leadership with money, narcissistic strokes and a sense of authority, sexual opportunities, and free labour. (I have a non-scientific theory that this is how religions propagate. They're such an effective way to provide all of the above that whatever the dogma, the social dynamics are just too attractive for weaker individuals to ignore.)

Aside from money, it's hard to see how that applies here. (If Yudkowsky was running this personally I'd definitely be concerned.)

But while there are obvious culty elements here, there doesn't seem to be a funnel which uses introductory bootcamps/workshops to find the most suggestible converts so it can sell them more and more expensive follow-ons. There also isn't any sense that there's a "reward" scheme where loyal followers are allowed into an inner circle - from which they can publicly purged if they misbehave.

It looks more like there are some interesting brain hacks on offer, packaged into a format that's maybe too intense to be ideal.