I’ve never heard of trying that. Yes, it could work. Maybe. Is there some hidden area you could try the technique on first? Some place that will be hidden by a chair or cabinet or rug if it doesn’t work?
I’ve used stain to make grain over a patch, and it worked well, but never over a water stain. Blending the patch into the original floor is a challenge, that’s for sure. The poly might dissolve the latex paint but as long as the paint is totally dry and the poly is put down carefully it should work. SHOULD. Doesn’t mean it will.
Try the combination on a piece of Oak and see what happens. That’s the best I can offer.