Admittedly I don’t know much about cryopreservation (looked into it many years ago as a curiosity) but my understanding, and the article says the same, is that they clinically die first and then it’s a rush to preserve them before too much breakdown happens. Since it’s quite expensive, most people only preserve their brain or head, which is removed before being frozen. I’m not sure legally they would be able to do this pre-death, since the harvesting/preserving would directly cause death as we currently understand and classify it, and assisted euthanasia of any flavor is illegal in most places.