My feeling on, this, and piracy in general, is that the people pirating your game aren't likely to have been paying customers in the first place (especially releases for decades old hardware). Whether or not they "deserve" to be able to play the game or not, it's unlikely you'd see a decrease in revenue. There's also the people who are interested enough to emulate it, but not pay the money for a physical release, might end up grabbing a copy because they liked the game so much. Hell, most of my collection is stuff I pirated as a kid before I had any money and played in emulators.
That being said, people making repros with said dump, when the game is readily available from official sources is scummy as all hell. If that's the case with this person, I wouldn't sell, or I'd at least sell a "personalized" copy. Otherwise, I'd say go for it, and possibly upload the ROM yourself so the people searching for the ROM get it from you and are even aware physical releases exist, and get familiar with you as a developer.