Non flame question, every time I have played a grey jedi in a game I have walked the line of using both sides of the force. This game also makes it possible to be grey in affiliation, allthough poorly implemented, so does that just not fit into cannon at all?
The alignment system is a game mechanic. Jedi and Sith can not "walk the line."
Edit: Plus all of Revan's canon deeds in KOTOR are Light side choices.