Clogged sink strainer

geoB

When dewinterizing our 2020 T@B 400 BD, the sink in the bathroom flooded. Turns out the strainer was clogged; sink did not flood when winterizing. The strainer cannot be removed for cleaning - the fold down sink leaves a narrow access to the top of the strainer. The panel below the sink provides access to plumbing below the sink but trying to loosen the nut on the strainer only spins it.

The good news is that the top of the strainer could be cleared with a finger-powered rag. But is there any way to actually remove and reinstall the strainer?