Off the top I wonder if an idea might be to do the following, keeping in mind that the registrar would charge extra but ultimately it would be to the registrants benefit and less disruptive if the normal ways (that have no cost) were interupted:

- Send postal notice (some do this already) - Send express or certified letter (charging up front to be notified this way) - Make phone call - Send email to any contact addresses on the website

I would like to point out also that this is a reason also why "privacy" on whois is a bad idea in some cases. In this case it is fairly easy for a third party to get in touch with the joyent contact (someone might know him or have an alternative means of contacting him - even by phone if not the whois phone number). If contact info is protected by privacy that becomes a different issue (you would have to have more specific knowledge).