If I were to fathom a guess, it would be because Ubisoft has dibs on putting MJ on any videogame-related product...i.e., The Michael Jackson Experience. If that were it, would be ironic since MJ's material is under Sony's label
That game never happened (and I believe that never will) because Michael Jackson The Experience is pratically a 2 in 1. Just Dance: Michael Jackson + SIngstar Michael Jackson.
The game uses the dance engine of Just Dance and the singing engine of Singstar.
I recommend! It's pretty funny!