IPR licences are complicated and maybe Sony did not have contracted rights to the music on MD format but had committed $$$ to the campaign? Maybe Jackson had good lawyers when he sold them the catalogue!!
Are MD pressed or recorded? It might be interesting to see if two Michael Jackson promo discs are identical.
Pre-mastered MDs are pressed and the format is physically similar to CDs. I would be interesting to put this disc under an optical microscope, I assume it would look similar to a regular pre-mastered disc but perhaps it's actually a recordable MD (which look very different) or some kind of R&D experiment.
I took a bunch of optical images of MDs and other formats here for reference:
Are MD pressed or recorded? It might be interesting to see if two Michael Jackson promo discs are identical.