Earlier quoted context omitted.
My reading of it on their page was that they are free to ignore your bug report unless you donate to them. You didn't pay? Well, that's just, like, your bug report, man... Essentially it boils down to: you cared enough to submit a bug report? Then you should also care enough to donate.
That logic (your last paragraph) essentially assumes that people only care for selfish reasons. Plenty of people contribute for the sake of giving back to the project (by e.g. taking the time to write a high-quality bug report or PR).
True and in this case, if the team thought it was good they can still choose to run with it. But that would be unexpected.
This is about managing expectations. And generally in the modern world, if you want someone to fix something for you, you pay them.