More infringing than emulators. De/recompilation projects are pretty clearly 'derivative works' of the original copyrighted program code, even if they require the original ROM in order to extract other assets necessary to compile a fully playable artifact.

The closer analogy would be fan-translation patches, which are also pretty clearly copyright-infringing derivative works though generally tolerated by rights holders.

Companies often encourage (or at least turn a blind eye to) creative derivative works from fan communities, especially if they're non-commercial and aren't cutting into the market share of their own official products enough for them to take notice.