cryonics hits quite a few green-ink heuristics (unfairly, IMO, but it does) which gets it filed with the mental spam in short order.
Even the stupidest pseudosciences or movements have received excellent debunking; for example, I would put the Urantia cult way down the list below cryonics, and yet, we still have Martin Gardner's 500 page examination/debunking, Urantia: The Great Cult Mystery.
(I would point out, incidentally, that 'nobody will criticize low-status things' is a fully comprehensive proof of the non-existence of the entire skeptics movement, which is pretty much all about criticizing low-status things, and you probably would prefer not to use such a claim as your explanation of the lack of good cryonics criticism...)
A quite obvious possibility is that would-be debunkers who want try to go deeper than Penn and Teller style mockery soon realize that they would have to engage much more seriously with cryonics than with Urantia to try to debunk it - sound like they were taking it seriously - implying a far greater loss of status than soaring casually above Urantia, effortlessly trashing it without a hint of sympathy.
"Everyone who's tried to 'debunk' this seems to have ended up writing casual mockery, and oddly enough no would-be skeptics ever seem to engage the argum...
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