While it may add an extra step on their end process wise, it seems like the obvious solution to this matter is to simply enact a policy such that if domain ownership changes hand the associated accounts are reset unless a signed transfer of ownership and proof of identity is provided by the original owner.
I hadn't considered the case of updating whois information. However, to resolve that issue I'd simply provide a mechanism where you could flag your account as pending an authorized whois update. Then, when the whois is updated, google would not take any action since the update was pre-approved by yourself.
That's still about the worst way to handle it. A change in one unrelated area can completely wipe out services in another. Just to protect against the edge case that you didn't delete your account, want to keep your data protected and let your domain expire and be registered by someone else. Don't hurt legit customers to protect a fool.
I suspect the real problem here is that identifying when ownership has changed is pretty much impossible unless you are the registrar. Assuming you could even fetch them (they probably are rate limited) the whois record could change without indicating an ownership change or even the DNS could change without indicating an ownership change. Also, even if there was no change in these records, the owner might have changed. The new owner, if an attacker, could put the same data into the whois record and use the same DNS records. The domain may never even "expire" officially with some registrars letting a new owner grab a domain before the official expiration drop.
I assume the previous owner probably has some mechanism for deleting the accounts that are currently on Google Apps. If that's so, then it seems reasonable that it's their responsibility to do so.
Everything I've ever read about Google's customer support infrastructure is that they don't "do" person-to-person transactions. Hardcopy? You must be joking.
That seems to square with my experience. Google Apps is free for nonprofits up to 3000 users, though they start you out with something like 100. I hit the "request more users" button and I was up to 500 almost instantly (though it said "we'll get back to you" after I hit the button.
