Well, maybe going all-in in building a "high-value software infrastructure project on [your] own" is not a good idea if you don't have any concrete plans for funding right from the start? Changing the license to a non-FOSS is basically the most knee-jerk reaction you can do in that case. Find a maintainer. Give the project to the community. Become a regular contributor in your own spare time instead of the main (and sole) developer.
There are so many better ways to handle such a situation.
If you replace "building software" with "building a road" (or some other similar real-world infrastructure project), everyone would agree that it's a self-made problem and that there are other ways out rather than just "from tomorrow on this will be a toll-road". You can turn the road over to your city/municipality. Or you could let other take over the maintenance. If the road is useful, there will be others. If it isn't, well, everyone moves on.
Why? Did the community give to him? It certainly sounds like it hasn't. What obligations does one have to a community that doesn't give back?
> There are so many better ways to handle such a situation.
Better for who? You? Or him?
If open-source communities want open-source, they're going to need to come to grips with the need for people to eat, and to do that they are at minimum going to need to pass the hat. If they're not going to do that, this happens, and telling somebody who isn't you what they should do for "the community when "the community" doesn't support them is, frankly, wrong verging on immoral.
You are 100% free to fork the last permissively licensed commit and maintain it yourself. Looking forward to seeing you put in some work with the same enthusiasm that you use to tell people how to run their projects.
> Changing the license ... Give the project to the community
Wrong - this is a false dichotomy. "changing" license is not retroactive. Older releases are still available to the community and anybody can fork the project and carry on a new release train.
There are so many better ways to handle such a situation.
If you replace "building software" with "building a road" (or some other similar real-world infrastructure project), everyone would agree that it's a self-made problem and that there are other ways out rather than just "from tomorrow on this will be a toll-road". You can turn the road over to your city/municipality. Or you could let other take over the maintenance. If the road is useful, there will be others. If it isn't, well, everyone moves on.