But what you really want is a throwaway line where it doesn’t matter. Which means the whole “who are Rey’s parents?” plot might end up being “Luke and a random lady” for 95% of the audience.
What I really want is “not Luke,” but if Luke is the father, who else would be the mother other than a random lady? Unless there’s a woman on the island we don’t know about who’s been living with Luke all these years.