As far as I understand it, CFAR's current focus is research and developing their rationality curriculum. The workshops exist to facilitate their research, they're a good way to test which bits of rationality work and determine the best way to teach them.

In this model, broad improvements in very fundamental, schoolchild-level rationality education and the alleviation of poverty and time poverty are much stronger prospects for improving the world

In response to the question "Are you trying to make rationality part of primary and secondary school curricula?" the CFAR FAQ notes that:

We’d love to include decisionmaking training in early school curricula. It would be more high-impact than most other core pieces of the curriculum, both in terms of helping students’ own futures, and making them responsible citizens of the USA and the world.

So I'm fairly sure they agree with you on the importance of making broad improvements to education. It's also worth noting that effective altruists are among their list of clients, so you could count that as an effort toward alleviating poverty if you're feeling charitable.

However they go on to say:

At the moment, we don’t have the resources or political capital to change public school curricula, so it’s not a part of our near-term plans.

Additionally, for them to change public-school curricula they have to first develop a rationality curriculum, precisely what they're doing at the moment - building a 'minimum strategic product'. Giving "semi-advanced cognitive self-improvement workshops to the Silicon Valley elite" is just a convenient way to test this stuff.

You might argue for giving the rationality workshops to "people who have not even heard of the basics" but there's a few problems with that. Firstly the number of people CFAR can teach in the short term is tiny percentage of the population, not where near enough to have a significant impact on society (unless those people are high impact people, but then they've probably already hear of the basics). Then there's the fact that rationality just isn't viewed as useful in the eyes of the general public, so most people won't care about learning to become so. Also teaching the basics of rationality in a way that sticks is quite difficult.

Mind, if what you're really trying to do is propagandize the kind of worldview that leads to taking MIRI seriously, you rather ought to come out and say that.

I don't think CFAR is aiming to propagandize any worldview; they're about developing rationality education, not getting people to believe any particular set of beliefs (other than perhaps those directly related to understanding how the brain works). I'm curious about why you think they might be (intentionally or unintentionally) doing so.