If you're an "MJ vocals expert analyser" as a member once wrote, you can tell FAT vocals are not from the 80s. The way he sings and how Mike's voice changed is spot on early 90s
Regarding why MJ put it on T25, I have a feeling he was requested to put one more unreleased song, and he just "gave" them FAT
I just don't believe MJ even put 1/10 of his heart into T25 come to think of it. Just no way. He approved it and all of that, but Michael must have been other places in his mind during those days. "Sony, I just need something to boost me off quickly to regain some popularity before I blast off"" - or something like that.
His redemption was going to be TII and new albums/songs from there on... :/