I wasn't aware the dev "Owed us, and has to show proof (backup) of there hard drive crashing or a doctor's note for illness or whatever you call an excuse.
The easy answer is as an ADULT I am responsible for MY money and where it goes. PERIOD. When I want to start support I start support when I end support I end support. It's about being responsible for YOURSELF and your finances.
You said " Fortuitously, just as I was preparing to "Sponsor" it, the updates pretty much went glacial and I also came to understand how the sponsor model can be exploited." Demonstrating you didn't feel the update times were worth your money, hooray for you.
On the other hand this is an ADULT forum catering to adults that should know how they want to spend there hard earned money. Well intentioned or not, the Dev doesn't force supporters to continue support and it's easy enough to cancel. A dissertation on how money workers is unnecessary imo.