I feel like the takeaway here should be that the experience of contributing to the project was not great. That’s it.

I don't think this is a valid summary. I think the first-time contributor had a rather self-centered approach to the bugfix, and turned a run-of-the-mill bugfix in a huge drama-riddled personal attack on a FLOSS maintainer for no good reason.

Only in the OP's one-sided and vindictive account of the whole ordeal does the project maintainer have questionable behavior. The central theme of the one-sided account is also absurd, as if a kernel maintainer needs to wait around for first-timers to contribute a patch for them to "rob" it to have a commit to show for.

The whole soap opera is so regrettable, and the OP comes out not looking good at all.