Why would they intervene? They get their cut. If they kick Bones out, they will stop getting their cut and they like getting their cut.
There's nothing in Patreon (or Subscribestar) rules to say that the dev can do sweet fuck all with his money and membership is up to patrons' discretion.
That's the concept of patronage, remember? To give a creator financial freedom to do whatever he wants and getting access to his production in exchange. Plenty of wealthy patrons over the years were duped by complete fraudsters who conned them out of tons of money. Bones is just proudly following in their footsteps.
Joking aside, there's nothing in the rules speaking out against hiatus. The best practice is to suspend paid subscriptions during a hiatus, but this is not an enforced rule. None of these services enforce any sort of notifications from the creator that they're on hiatus and they certainly don't notify of any hiatus on their own.
You may have confused crowdfunding through a patronage subscription with a game purchase where you're entitled to a specific product and where you can voice your dissatisfaction and even demand a refund. With patronage, you're paying a lot more money, but at least you're getting much worse service in return.
