It is argued that Jason Malachi's flow is different in his songs than in the Cascio songs.
Okay, I get that.
But let's remember that artists evolve a bit from project to project.
Listen to Off The Wall, then to Thriller, notice the different styles, the different type of vocal. In Thriller, Michael's voice is even more refined and clearer than in Off The Wall, he has perfected it even more.
In Bad, Michael goes an even step further and takes the aggressive "Bad" theme to it's full level. The vocals sound even better on this album, his vocal tics are all over the place, he owns it.
Compare this to Jason Malachi.
In his first songs from his debut album, the vocal mixes are a bit low, he doesn't sound as professional, the beats aren't as good, his songwriters likely weren't as good. He is still learning how to make a record.
Then comes Critical, he is more on top of it this time, his vocals sound stronger, more processed, the production is better, it's more promoted, he puts more effort into it, etc.
Now, if Jason Malachi was asked to record vocals for the Cascio songs, don't you think there'd be a slight difference in sound than on the Critical album or his first album? Yes, most likely, but would he sound like a completely different person?
My point is, from Thriller to Bad Michael sounds different, from Dangerous to Invincible he sounds different, more evolved, but you can still prove that it's Michael Jackson, he still leaves an obvious trail.
In the Cascio songs, while Jason Malachi might sound a bit different than in his first album and Critical, but he still leaves his trademarks everywhere.