I don't think that 2) really captures the objection the way I read it. It seems that on margin, there are much more cost effective ways of engaging math olympiad participants, and that the content distributed could be much more directly EA/AI related at lower cost than distributing 2000 pages of hard copy HPMoR.
I don't think anyone should be trying to persuade IMO participants to join the EA community, and I also don't think giving them "much more directly EA content" is a good idea.
I would prefer Math Olympiad winners to think about long-term, think better, and think independently, than to "join the EA community". HPMoR seems ok because it is not a book trying to convince you to join a community, but mostly a book about ways how to think, and a good read.
(If they readers eventually become EAs after reasoning independently, it'...
I'd like to challenge the downside estimate re: HPMoR distribution funding.
I think that funding this project comes with potentially significant PR and reputational risk, especially considering the goals for the fund. It seems like it might be a much better fit for the Meta fund, rather than for the fund that aims to: "support organizations that work on improving long-term outcomes for humanity".
Could you say a bit more about what kind of PR and reputational risks you are imagining? Given that the grant is done in collaboration with the IMO and EGMO organizers, who seem to have read the book themselves and seem to be excited about giving it out as a prize, I don't think I understand what kind of reputational risks you are worried about.