Michael "studied the greats" himself. He was a collector. Do you really think he didn't listen to every outtake or look at every sketch he could find of the artists he admired? He must have known other people would want to do the same with his work in the future - it happens to every great artist. If he'd had extremely strong opinions on this, wouldn't he have included something about it in his will?
At the same time, it is of course possible that he simply had not fleshed out his opinions on this matter by the time he passed. In the end, we simply cannot claim to know with certainty how he would have felt, because afaik he never talked about what he wanted to happen to his work after his death explicitly. What does seem clear to me, is that you cannot compare him being upset about leaks, or not in favor of demos/outtakes being released while he was alive, to the release of such material posthumously. It's a completely different animal.
You can of course say the same for remixing or 'completing' material - we cannot claim to be fully certain that he would be against this just because there are indications that he really disliked his work being tampered with when he was alive. Still, I think there is an enormous difference between releasing demos and outtakes as they were left behind (saying: look, this is something this great artist was working on, these were his ideas, this was his process and why he was so amazing) versus taking the liberty to finish or demolish the work he did without spotlighting his artistry and releasing it as the 'new MJ record', having a hologram of an impersonator dance around to a remix of an old outtake, etc. The latter approach reduces the work he left behind to nothing more than a cheap money-making commodity, rather than a fascinating peek into the creative process of a masterful artist...