You do not MEAN **cryogenics**, which is low temperature physics: "The branches of physics and engineering that involve the study of very low temperatures, how to produce them, and how materials behave at those temperatures". By contrast, cryonics is "The emerging medical technology of cryopreserving humans and animals with the intention of future revival."
Cryonics as practiced seeks to avoid "freezing", which involves ice formation. Ice is damaging to tissues. Possibly some future molecular repair technology could fix that damage, but it is more prudent to avoid the freezing damage in the first place. Therefore, cryonics organizations first perfuse cryonics patients with anti-freeze cryoprotectants to eliminate ice altogether (vitrification). Today, it is not possible to revive a person who has been vitrified any more than it is possible to revive a person who has been frozen. But electron micrographs of vitrified brain tissue at least indicate that brain structure can be preserved on a fine level, which makes future molecular repair more promising.
Average human lifespan has doubled in the last couple hundred years, and there is no evidence in the Bible that this is against the will of God. Nor is there anything in the Bible that would indicate that God would be offended if humans lived hundreds or thousands of years. Methuselah reportedly lived 969 years. What is a few thousand years in the face of eternity?
Where in the Bible does it say that you go to heaven or hell immediately after the heart stops beating? There is talk of a "judgment day" so maybe no one is in heaven or hell until that day arrives -- perhaps at the time of the Second Coming of Christ. That could be 100 years from now or it could be 100,000 years from now. There is no agreement about what happens to souls between the time of death and the time of Judgment Day. They could remain in a suspended state (like a frozen embryo) awaiting Judgment Day -- unless they are revived with a defibrillator after several minutes or a post-cryonics treatment after several decades.
The Catholic Church is opposed to the destruction of cryopreserved human embryos because they are believed to have been given souls at the moment of conception. Human embryos could be stored in liquid nitrogen for 100 years before being placed into the uterus of a surrogate mother. This is not necessarily so different from cryopreserved adults who could be restored to life after 100 years. Or from a child whose heart has stopped while being hypothermic in a frozen pond. Does that mean that their soul was in heaven or hell for an hour until it was brought back? Is that so different from a cryonics patient being "restored to life" after being cryopreserved for 100 years? What is the difference between one hour and 100 years in the context of eternity or in the mind of God?