You are underestimating just how enormously Peggy would have to change her mind. Her life's work involves emotionally comforting people and their families through the final days of terminal illness. She has accepted her own mortality and the mortality of everyone else as one of the basic facts of life. As no one has been resurrected yet, death still remains a basic fact of life for those that don't accept the information theoretic definition of death.

To change Peggy's mind, Robin would not just have to convince her to accept his own cryonic suspension, but she would have to be convinced to change her life's work -- to no longer spend her working hours convincing people to accept death, but to convince them to accept death while simultaneously signing up for very expensive and very unproven crazy sounding technology.

Changing the mind of the average cryonics-opposed life partner should be a lot easier than changing Peggy's mind. Most cryonics-opposed life partners have not dedicated their lives to something diametrically opposed to cryonics.