All I can tell you is the 'custom' in Custom Domains refers to the idea that you can set whatever security policy you would like. That includes restricting who can change your domain to a list of people you can count on one hand who each have a personal relationship with you. If you want a policy which requires a photo of you with today's newspaper in it to change a domain, that's probably something which can be arranged.
Just to clarify for readers, this is the Custom Domain plan, which is the Enterprise version of the Registrar we are launching today.