If you don't like the way a project is being run, fork it and own it yourself.
I know that's harsh, and not idealistic, but it's the way people should really think about this. People take FOSS for granted, CONSTANTLY. And maintainers even more so.
However instead of raising a "don't work, please fix" bug s/he took the time to do all that.
Anyone that went to such length deserve basic courtesy, whether the code is accepted or refused.
Refusing a patch because it is "boring" is not respecting the time people dedicated to your project.
I would understand refusing because the patch makes an unwanted compromise on performance and the maintainer considers performance regressions as bug.
I have replied to logged issues with the question: "I don't work on this, unless you have set aside a budget that pays my hourly rate".
If the maintainer had said, "Hey, I don't have the time to review/test/verify this PR so I'm closing it for now," the backlash probably wouldn't have been quite so severe.