Thanks for your input! My intention wasn't to ignore the mold, but to try to seal the leak in the least invasive way. Releasing the spores was one of my main concerns. I'm moderately allergic. But I'm seeing that there's no way around ripping up the floor, even if just to help find the leak and treat the mold.

The rot didn't seem to go too deep or spread far, but very localized. Luckily, the very bottom subfloor seems to have a coating over it that prevented water from affecting that layer.