[...] there's still the question of whether at the margin advocating for cryonics is a worthwhile endeavor. My intuition is that we're so far away from having a population interested in signing up for cryonics (because of the multitude of irrational biases that people have against cryonics) that advocating for cryonics is a very inefficient way to work against existential risk.

The margin has to take into account all future consequences of the action as well, not just local consequences. Again, a concrete problem I have with your post is essential misrepresentation of Hanson's post by quoting current costs of cryonics, and not mentioning the argument for lowering of costs. This you haven't answered.