DO sends an email when they can't charge. They send a second email 21 days later, when the account gets suspended (which doesn't deleted anything), with essentially your message, except it's 14 days instead of 60.
It's five weeks really poor form but eight acceptable? Seems a bit subjective.
DO reserves say $20 (just an example) when one spins up a new droplet, and if one forgets to pay — then, DO shuts down the server. But keeps the backups, until the GB-month cost is $20.
One could choose how much money to reserve, depending on how important the data one stored on the droplet, was. If it's just for running test: $0. Customer data: Maybe $$$ instead.
There could be a default that made the backups stay for 3 months?
Any remaining money could be refunded, whenever one wants.
6-week vacations aren't that uncommon, which is a scenario I would expect to encounter if I was DO. If that email doesn't get seen for 6 weeks it definitely shouldn't result in all backups being deleted. Beyond that, it's not unreasonable to imagine health issues or other external circumstances putting someone out of commission for 6 weeks (or even more, making it quite subjective).
All in all, from the moment of non-payment to the moment that everything you have on their servers is gone shouldn't be less than 90 days in my personal opinion. If that raised the cost of my backups by a few dollars, so be it. The backups are there to account for things I may not have been able to consider.
I may have said vacations, but people take time off work for any number of reasons. Paternity/Maternity leave, health, family needs, and so on. I had a 2-month lapse when I moved from Germany to the United States for example.
If there were, for any reason, an internal lapse in communication or processes (imagine small companies...) that could result in a pretty sour situation.
This discussion could be easily settled by comparing the grace period to the ones provided by Vultr and Linode. Then compare all of them to Amazon, which I would bet blows everyone else out.
It's five weeks really poor form but eight acceptable? Seems a bit subjective.