(Assuming that you meant to say "still alive" and interpreting this as "had ever been done on somebody who wasn't clinically/legally dead"; not sure that that's what you meant, but if not, I don't understand your comment:) Qiaochu has already explained that he was talking about information-theoretic death there.

(ETA: If you meant that nobody's actually been brought back to life, that still doesn't seem to conflict with the correct-by-definition claim that cryonics doesn't work after information-theoretic death.)