After all, when they do team up they do seem poised to try it anyway.
The difference is that they were going to do it as Jedi. To quote Palpatine, “Your hatred, your anger, you want to kill me. That is what I want.” That seems to be the requirement for transfer, one which they might fall under as Kylo and Rey standing side-by-side rather than Ben and Rey.
Regardless, removing Kylo’s fixation with becoming a Sith is more than enough for me.