So I don't think that there's any at all likely scenario where there's a disaster that causes a sudden influx of cryopatients and doesn't trigger one of the other failure modes. I have trouble even imagining what that sort of situation would look like- maybe an meteorite striking a cryonics convention?

How about a deliberate attack at a cryonics convention? There was stuff about nanotech researchers getting bombs in the mail, I don’t see why it wouldn’t happen to cryonicists, especially a couple of decades from now when it cryonics might be more popular (i.e., higher on the public radar) than now.

On that note, at first thought it doesn’t seem like it would take enormous effort for someone to sabotage a cryonics facility. (Remember, you don’t have to destroy it completely, you just need to partially thaw for a short while or otherwise damage the what I imagine are closely-packed brains; given they’re stored in liquid nitrogen, even just fracturing the dewars might be enough: you can’t quite send someone to fix them until the temperatures rises a lot.)

This might not be a big risk today, but if cryonics does get even a little bit mainstream in the future it’s easy to imagine all sorts of people who might want to do that.

(A well-meaning if not quite reasonable person who just wants to save the thousands of frozen people from missing on Heaven is what my brain popped out right now. I’m sure reality will find something even sillier.)