Is it ok to use fixed gear threads for a freewheel? I have a fixed/fixed flip-flop hub and the lockring threads are stripped out on one side. Would I be ok to just thread a single-speed freewheel on that side and use it as a fixed/free hub?
If the thread fits, there would be no problem.

The nature of the mechanical stresses over the hub during traction would be identical (only there would not be the backpedal component, but that means less stress, not more).