Thus their argument is not really an argument based on evidence—it is more of an argument based on expectation. Now, this expectation may very well be solid and well justified, but in my experience, the LW community tends to really bastardize the argument and claim that the evidence is somehow solid and well worked out.
Cryonics either works, or does not; there’s no way for it to work “on current evidence” but not work on some other set of evidence. Perhaps you mean that cryonics hasn’t worked yet, but this is also what you would expect to see if it would eventually work.
In part, this seems to merely be a disagreement over the definition of “evidence”.