Well it's definitely a flaw in their procedure. However, they're already set up to assume that everyone should have Whispernet access, and avoid selling to people who do not. So while year, if I were in the company, I'd point out the potential problem in advance and make sure Kindle deregistration was part of the procedure, I can also easily see how this issue was ignored because it shouldn't happen in the first place.
You might try submitting your tale to consumerist.com. It might generate attention from Amazon who might be able to give you some partial satisfaction.