Probably a version of the selection bias. The cryoskeptics could be unwilling to be drawn into a hostile online discussion, or even be wary of getting downvoted.
This seems like an information cascade, and hence like an epistemic tragedy if true. Can you think of things that are uniquely predicted by this theory, or an observation you could make which would falsify the theory if the observation came out in a particular way?
When I've brought up cryonics on LessWrong [1][2], most commenters have said I'm being too pessimistic. When I brought it up yesterday at the Cambridge MA meetup, most people thought I was too optimistic. (I think it could work, but there are enough things that could go wrong that it's ~1000:1 against.) What makes the groups so different on this?
[1] Brain Preservation
[2] How Likely is Cryonics to Work