there is no coming back from that today.
it is not impossible for a regenerative process to one day be capable of solving this issue. it is also not impossible that the cryo methods will improve over time to reduce the amount of damage done. in time the two points will meet along the way somewhere and we will have the first restored person.
they may have the total iq of a pile of regurgitated watermelon, but they will have functioning neurons again in a way that resembles life.
the alternative for most of these people would be a box in the ground or a tube of ashes, how is that fate any better then one that gives science a playground?
i would do it. there are things that we can learn in this process. It might not be about eternal life but it could continue to help develop medical processes that further aid in combat medicine, traffic accident survival, advanced forms of cancer surgery or organ transplantation. If my body is dead anyways why not?