In a more perfect world, the suspension procedure would be able to start before legal death, which should reduce the damage from ischemia even more because there wouldn't be any time when the heart is stopped and the body is warm. Not long term memories. When children nearly drown in cold water, they can often be revived after having no apparent metabolism and still have their memories. Likewise large doses of barbituates can suppress all measurable brain waves without destroying long term memories. Repairing the freezing damage looks much harder than curing any existing disease, so if revival is possible then curing the disease ought to be trivial.
Old age is a disease that ought to be easier to cure than the freezing damage.
He was a cryobiologist. The analogy is not valid. Some animals can survive freezing, but no animals can survive grinding. Freezing in liquid nitrogen preserves some information about the structure of the brain, which may make it possible to recover memories from that brain. Mummification involved pulling the brain out of the nose in little pieces, so the best that could be expected from a mummy is to build a clone and to give it plausible memories.