I guess 2000 Watts isn't MJ also.
Contrary to the three forgeries released on the Michael album, 2000 Watts was actually released by Michael Jackson during his lifetime and it does, actually sound like himself.
Even if the voice is deeper, you can hear that it is his tone, his vibrato, his belts and his way of articulating words. Before you ask the question “is there any proof that Michael didn’t sing these songs” you must ask yourself “is there any proof that he did sing them?” No. There isn’t.
Apart from Cascio, saying that he recorded them, there are no other witnesses to these sessions and no authentic notes written by Michael Jackson mentioning any of these songs.
Additionally, the process of recording described by Cascio, is not even close to Michael’s habitual way of working when recording music.
I did have to repeat myself in this post, since I remember writing something similar a while back, without you acknowledging it.