I read “Splinter” after seeing ROTJ so I just chalked it up to the writer not knowing what was to come (the way Luke & Leia didn’t know they were siblings).
I saw ROTJ on May 25th, 1983. Loved it then, love it now. I never had a problem with Luke & Leia being siblings.
EDIT: I just noticed this thread is from 2007. lol.