I'm no expert, but it seems reasonable to me that, if brake rotors can warp more easily after being turned(as many people experience), flywheels could perhaps show problemseven if they are resurfaced. The issue with rotors becomes one of spots which have the 'temper' or grain structure of the metal altered and it can go deep into the metal. So, even after having some material removed, that area can more easily have pad deposition or other problems. I suppose a 'burned' flywheel could have similar issues.
I'd say just have a discussion with your mechanic He will likely have a lot of experience with this problem. Let's suppose the rae main seal or some other (?) source has soaked the disc with oil. It's unlikely that would harm the flywheel I guess. Also, just because some aftermarket FWs are half the weight of OEM FWs doesn't mean the clearances or other design criteria would allow half the thickness of a FW to be removed. I dunno.