Like you I always assumed it's Martin Kopell.
First Stardust releases appeared in the early 90s, or at least that's when I saw them for the first time. Tempests around mid 90s at a guess.
IMO Stardust is nothing but a bootleg label, period. They might be legal in Canada due to a loophole in copyright laws but surely aren't licenced at all. Bit like the belgian Marginal CDs from the 90s. If a record is re-released w/out consent of owner of rights it's a bootleg.
Whoever bought that specific Tempests 45 on Ebay bought it to dj with. "45 has better sound quality than the LP", that's just bullshit unless the only copy of the LP one has ever played was a G- US mono press. I've owned/heard various presses of the LP over the years, canadian, dutch stereo, german stereo and they all have supreme sound quality.