Possible reasons for fake song
Only 1 reason comes to my mind:
Sony is testing us. They want to see if we would recognize MJ voice - if we would not react like we did, we would get a million of fake songs.
Now, i'm pretty sure MJ did not left so many songs behind. Yes, he said he has hundreds of unreleased songs... But he was often overreacting, we don't know how many songs he actually had in his vault. More important, we can't know if those were finished songs or only demos, bits of melodys etc...
Now think about it: Most of pre 1991 songs can't be released, as they sound outdated. There might be a few exceptions, but not many.
Also, let's not forget how many MJ songs did leaked in past years and how many songs he released on rereleases and Ultimate collection etc...
I highly doubt that MJ finished all outtakes. He simply recorded demo, didn't like it too much so he put it into his vault. Years later he reworked on some of them, or simply put some parts out of this unreleased songs and mixed them into another song. How can we know that there is not song that would had the same main melody as let's say You rock my world? When MJ was working on Vince, he might just took the melody out of that outtake and put into brand new song (you rock my world).
If that's the case, a lot of outtakes has already been released and a lot of them can't be released (outdated sound or they are simmilar to songs he already released).
But my theory has one huge hole - why would sony paid so much money then?
On the other side, they might focus on other projects?
What do you guys think?