I really hope that in the next game they add this as a "3rd option." A neutral Jedi should get a bonus on the "universal powers" and maybe have reduced penalties on using light or dark side powers. A grey Jedi is what it seems Kreia is trying to turn you into anyway. And you should still be able to go to the tomb. I think that part was crap on this game. What was to keep me from just walking in? I mean, even if you're neutral, if you're the most incredibly powerful neutral Jedi ever, whose going to stop yoU?