After what he did to Officer Jonston, after the damage he'd caused to the ship's computers, they decided that Ren was too dangerous be left loose.
So they put him into a stasis chamber -- that would keep him out of the way until the ship's autorepair systems had finished their work.
Time shouldn't pass inside a stasis chamber, but Ren realised that time was passing...
He forced the chamber open and found himself stranded on a planet where the apex of technology was a wooden windmill, and where the inhabitants thought the concept of interstellar travel was ludicrous.
Ren had no clear way of getting home, but he was a scientist, a technician...
He would find a way.