There's already enough evidence to locate the hypothesis - eg experiments on animal organs and small animals. Therefore your assertion that this is some crazy idea plucked out of nowhere doesn't hold.
The other hypotheses were located in similar manner, though. And far too much has to be ignored to generalize from said animal organs or said microscopic animals. Generalization from kidneys to brains is particularly dubious. Especially as great many of said frozen corpses are frozen corpses precisely because of their brain's unusual fragility with regards to loss of blood supply.
edit: The issue is not with cryonics in principle. The issue is with cryonics as it is. Similar to the people jumping off towers with some wings vs an airplane. Seeing a bird fly ...
In the past, the Cryonics Institute has had a policy that said that they would not accept anyone who is not a member. This has changed. The policy now is that someone who has full legal authority over your body can sign you up after you die. It costs $36,250 to be frozen if you are not signed up, which is more expensive. They also will not do anything until you have been on dry ice for 2 weeks after they have been contacted, so not being a member is more risky.
This is very important news for anyone who is currently cryocrastinating. It means that you can drastically increase your chances of survival without filling out any forms. All you have to do is tell a loved one you want to be frozen upon death, and that you would like them to take responsibility for making sure this happens. This takes literally 30 seconds. Do it now!
This news might also be a reason to not sign up right away, if you think something better (like radical life extension or uploading) will come along in your lifetime. We should discuss this in the comments.
Edit: The general consensus of this discussion is that this is a really bad reason not to sign up for cryonics.