Cryonics orgs that mistreat their patients lose their client base and can't get new ones. They go bust. Orgs that have established a good record, like Alcor and the Cryonics Institute, have no reason to change strategy. Alcor has entirely separated the money for care of patients in an irrevocable trust, thus guarding against the majority of principal-agent problems, like embezzlement.

Note that Alcor is a charity and the CI is a non-profit. I have never assessed such orgs by how successfully I might sue them. I routinely look at how open they are with their finances and actions.