"If the above is correct, it is rational to not sign up for cryonics only if:

1. You believe that P = 0, i.e. cryonics will never work; 2. You prefer being dead to being alive."

This kind of argument only discredits cryonics supporters. The "it might work" argument of cryonics is isomorphic to the "I might win the big one" argument of the Powerball. And while I think it's reasonable that the chances of cryonics working out are much higher than the chances of my state lottery investment scheme working out, that's at least partially negated out by the fact that one of them costs your whole life insurance policy to play (todo: see if I can set the beneficiary on my life insurance to Powerball numbers).