This whole thing was a feedback circle of increasing hostility between the community/contributors and this developer. At some points the developer was very unresponsive, leading to disappointment from the community, but then some very uncalled for personal attacks came from the community. I think the developer received some justified criticism, but I still understand his perspective, putting work in and getting abuse back sucks.
I'm not sure combining social media with code control is going to be such a good thing for a lot of developers who might not like to program in a fishbowl.
If he'd said "I'll write my own solution" rather than calling it boring, his response wouldn't have been a problem.
If you want to be able to place expectations on the author, pay them and get a contract.
But still so many PRs getting rejected, because they do not pass code review and usually it does not cause reporters of those failed PRs to open whole big flame discussion. That + overreaction on reddit was a last drop after which Nikolay decided to close the thing.
Looking at the postmortem[1], it looks like the patches provided were not good enough in the developer's eyes:
I believed it held mutable aliasing invariant and I was very happy that someone found real problem. I wanted to solve the problem, just with a bit of creativity. And use RefCell solution only if it would be not possible to solve it with any other way. Btw, I like the solution I found, it is in master and solves the problem at least one from the issue. If you want to push boundaries you have to touch this boundaries and sometimes you push too hard.
That sounds very much like the developer was headed to fixing them, but I guess the harassment and need for now won.