I don't think this will work out as the URL is generated via the Beatmap-ID. And the shown information is correct, you DID delete the beatmap.
If you change the behaviour of maplinks to default to the BeatmapSet-ID then it won't be possible to link single difficulties of a set anymore which would be very bad.
And I don't think peppy saves the references for unused Beatmap-IDs in the database, it would make more sense to delete the references once the map is submitted with one diff less.