I see what you mean. It's a matter of what threat you have in mind. I'm thinking mainly of the hostility of a pretty-much intact society to cryonics, and how to take your idea of protecting preserved people by using the notion of "respect for the dead" further, also incorporating the idea of honoring the dead by maintaining shrines/graves, etc.

You're totally right that if there's a global depression or civilizational collapse, then the threat of thawing comes more from inability to maintain rather than unwillingness or opposition.

Maybe it would help to split the post, or maybe organize this discussion, to investigate these ideas separately? It seems that engineering speculation about zero-maintenance cryonics is interesting and useful, and that using the "grave" analogy to make cryonics more acceptable and safe from interference is also interesting, but different issues and constraints arise for each of them.

Could someone design a stainless-steel prayer wheel that doubles as a hand-cranked device for condensing nitrogen from the atmosphere?

"We maintain this mechanism to honor our ancestors, that one day they may be reborn" sounds like the kind of thing some Shinto priestesses could've kept straight for all of recorded history, let alone a few centuries.