I admit that I am personally biased against Testing’s (and I suppose the official) interpretation of Palps ever wanting to possess Ben in a Rey Palpatine edit, because if he could just possess anyone regardless of their genes, why’d he bother putting all that effort into growing force sensitive clones of himself, or strandcasts like Rey’s dad? I also don’t really like the idea he ever intended to possess Luke in ROTJ - the existence of Exegol and his clone bodies there already help justify his seeming willingness to die in ROTJ; we don’t need to make it weird. In a Rey Nobody edit, though, I suppose you have to suggest he could possess either of them since there’s no obvious distinction.
Palpatine is very clearly shitty at making clones. It’s why his post-RotJ body is rotting to the point where it needs a life support machine, and why he can’t just make an army of Snokes.