My mind is blown that this question can still be asked after 20 000 pages on the subject. It's like somebody studying to convert to Christianity and then going, right before Baptism, "wait a second, so who is this Jesus guy again?"
All of those added MJ trademarks, from the hiccups to the yelps, from the "hee's" to the "aow's", were added to make the songs more complete, because the original vocals were incomplete, and MJ was no longer around to record the missing parts. Ad-libs are often the last thing recorded.
Also note that some of the songs DON'T feature those sampled MJ trademarks : All I Need, for instance, has none. And doubters use the ABSENCE of classic MJ'isms on that song to claim that THAT one is fake. So the Cascios can't win with doubters : if there are MJ trademarks on the track, either Malachi did them to fool the listener, or Eddie added them for the same reason. And if there are no MJ'isms, then it proves it's not MJ. So basically doubters can use everything and its complete opposite to prove their point...
By the way, to less conspiracy-minded people, the fact that those songs needed so many samples would indicate that they were NOT sung by an impersonator. Because obviously, if they had an impersonator at their disposal, they would have gotten HIM to sing all of the classic MJ screams and yelps and hiccups. Or maybe they were so clever that they purposedly asked him NOT to, so they could then add samples, and fool people who think that the samples prove it's really MJ...
Or it could just be MJ...