I guess it actually makes some sense related to rumors before the movie came out about Palpatine saying he was going to die and he was grooming Kylo Ren as a successor. Problem is the movie leaves us with a mess.

If we can flatten it to Palpatine wanting to kill Rey to resorting to her after Ben is redeemed, I think that’ll help a lot.

Moving the ‘spirit transfer’ line into the opening sequence already breaks the above plot outline, at least implying that Palpatine could take over more than just Rey in particular.