"utopia" in a "few" "simple" "steps":

• FAI builds something like minimal best perfect cryo that's possible physically.
• then it demonstrates to everyone on Earth that it's real and works (again, minimally).
• then it promises every on Earth that they'll be cryopreserved when they would otherwise die, if they want to be.
• then it does the minimum necessary to ensure that this promise can be kept, while also disrupting civilization's own technological development minimally.

it would need to do something to allow people to continue experimenting towards understanding cryopreservation, because it wouldn't be sharing details.

in general it's not handing over any details--not of cryo, not of the infrastructure it has no doubt needed to construct to ensure it can cryopreserve anyone who would otherwise die.

• then it asserts that it will do nothing else except continue to ensure the promise is kept.

of course this means protecting those who have been cryopreserved, and preventing anyone who wishes to be cryopreserved from dying without being crysopreserved.

while it will protect both its infrastructure and people wishing to be cryopreserved with any level of force up to and including cryopreservation of those who have wished to be cryopreserved, and murder of those who have not so wished, it will not extend this same level of force to protecting knowledge of the function of the infrastructure--though it will have obscured the details to try to impact civilization's technological development minimally.

the only gaping hole is: what does it do with the cryopreserved? at some point it seems like it should transfer their stewardship to civilization, but how does it make that judgment call? it certainly shouldn't hand over dewars to the first idiot who figures out how to defrost a body.