Whenever I reached 10,000 light side points, I still had around 60 dark side points. Whenever I received any more LS points, it subtracted that amount from my dark side total. Soon after I earned my "the pure" title from LS V. So I do not know what is going on with anyone else, but I have been able to reach Light V and I have made DS choices. Edit: it should be notes that my DS point total did not drop until I had 10,000 LS points