David says...

So you don't believe the mfgr's label?

I don't have the label in front of me, but the spec sheet on their web
site only forbids applying it _over_ an oxidizing finish. That would be
quite an omission if they make a product labeled sanding sealer then
neglect to tell us that you can't use by far the largest category of
finishing products (the many and varied polyurethanes) as top coats.
I'll admit I could be wrong, but I'll have to see it before I believe
it.