I might want to stop the human on the basis that it would violate his future preferences and significantly reduce his net fun. I don't have experience with the process (yet), but I think that cryonics is often funded through life insurance which might become prohibitively expensive if one's health began to deteriorate, so it might be considerably harder for him to sign up for cryonics later in life if he finally decided that he didn't really want to die.

The same would go for Clippy123456, except that, being a human, I know more about how humans work than I do paperclippers, so I would be much less confident in predicting what Clippy123456's future preferences would be.