Sony should really do it, but they have to do it in a way that wouldn't recieve the backlash that Guitar Hero 5 is currently getting.
Sony is a bit safer in that it owns the rights to Michael Jackson's music and probably the music videos so there's no need to get into a fuss about using his likeness or being playable. They'd still probably want to get the approval of the Jackson family though to be perfectly safe.
As for the game actually existing, there's almost no doubt that it doesn't. The listing for it on VGChartz was based on a rumor from a site that leaked a schedule for Sony's remaining 2009 releases that included SingStar U2, omitted games a few games, and contained a number of inaccurate released dates.











