I agree that a "long term fractional g spin test" is one of the most valuable things a LEO station can do. But there are others too.

For example, medical interventions against zero-g decay can be tested in any microgravity, spin or no spin. Development of in-space manufacturing and assembly can happen on any sufficiently capable space station.

All of that, however, requires a good amount of ambition. And I'm not sure if NASA under the current political system can deliver ambition.