I would agree with your reasoning if CFAR claimed that they can reliably turn people into altruists free of cognitive biases within the span of their four-day workshop. If they claimed that and were correct in that, then it shouldn't matter whether they (a) require up-front payment and offer a refund or (b) have people decide what to pay after the workshop, since a bias-free altruist would make end up paying the same in either case. There would only be a difference if CFAR didn't achieve what, in this counterfactual scenario, it claimed to achieve, so they should be willing to choose option (b) which would be better for their participants if they don't achieve these claims. But of course CFAR doesn't actually claim that they can make you bias-free in four days, or even that they can make themselves bias-free with years of training. Much of CFAR's curriculum is aimed at taking the brain we actually have and tweaking the way we use it in order to achieve better (not perfect, but better) results -- for example, using tricks that seem to engage our brain's mechanisms for habit formation, in order to bypass using willpower to stick with a habit, rather than somehow acquiring all the willpower that would be useful to have (since there's no known way to just do that). Or consider precommitment devices like Beeminder -- a perfectly bias-free agent wouldn't have any use for these, but many CFAR alumni (and, I believe, CFAR instructors) have found them useful. CFAR doesn't pretend to be able to turn people into bias-free rationalists who don't need such devices, so I see nothing inconsistent about them both believing that they can deliver useful training that makes people both on average more effective and more altruistic (though I would expect the latter to only be true in the long run, through contact with the CFAR community, and only for a subset of people, rather than for the vast majority of attendees right after the 4-day workshop), and also believing that if they didn't charge up-front and asked people to pay afterwards whatever they thought it was worth, they wouldn't make enough money to stay afloat.

When you've already paid for services, it's psychologically more difficult to ask for a refund than to simply not pay for services you have already received.

I recall I-think-it-was-Anna telling me that CFAR has given a refund to someone who didn't ask for a refund but who seemed unhappy with the service received.

(I don't claim that this fact makes that psychological trait entirely irrelevant here.)