In nature plants inbreed all the time. Take a pot plant for example. It flowers, dies, dries up, and drops seeds around the area. Next season those seeds sprout and will pollenate each other and the process starts over.
If a bee lands on a flower then flys to the one beside it....chances are you have inbreeding.
As for the Original Low Ryder. It is a stable plant with no hermie traits or non autoflower. Now when you start to cross them out with blueberry its a different story.
But if he pollenates a LR with a LR then he will get a short autoflower LR plant.