The truth is that people aren't anything like coherent enough to refuse cryonics for a reason like that.

I agree with almost all of what you say about no grand narrative and mostly just conformity, but I'm not willing to entirely dismiss this explanation as even a small part of the puzzle. It doesn't seem much different than the theories that poor people with few life prospects have higher temporal discount rates and are more likely to engage in risky/criminal behavior because they have less to protect. People aren't coherent enough to think "Well, stealing this watch has a small probability of landing me in prison, but my life now isn't so satisfying, so I suppose it's worth the risk, and I suppose it's worth risking a lot later for a small gain now since I currently have so little", but there's some inner process that gives more or less that result.

If even the few people who get past the weirdness factor flinch away from the thought of actually being alive more, I expect that would make a significant difference.

I'm going to try a test question that might differentiate between "cryonics sounds weird" and "I don't like life enough to want to live even more" on my blog. Obviously no one from here post on that since you already know where it's going.

If you want people to sign up for cryonics, the method with by far the strongest conversion ratio is to train them from scratch in advanced sanity techniques.

Alternate hypotheses: your followers are mostly technophile singularitarians, and technophile singularitarians are attracted to cryonics independently of rationalist training. Your followers believe there may be a positive singularity, which means the future has a reason to be much better than the present and avoid the unpleasantness Darwin describes in the article. Your followers are part of maybe the one community on earth, outside the cryonics community itself, where the highest-status figures are signed up for cryonics and people are often asked to justify why they have not done so. Your followers are part of a community where signing up for cryonics signals community affiliation. Your followers have actually heard the arguments in favor of cryonics and seen intelligent people take them seriously, which is more than 99.9% of people can say.