That's assuming if the LW appeared before him though if it attacked Sora out of confusion it'd likely attack Xehanort as soon as it sense someones presence.Well IF he did go back to the KG, I'm sure something had to be done about Terra's LW being there still. I know it was recently stated in that Terra's LW thread that since the battle with Terra's LW IS canon:
then MX would have not only had to settle there after KH2 (since why would he live there with Terra's LW running around there during Sora going there with DG, but he also probably would have dealt with Terra's LW.
MX wasn't around during kh2, he didn't return till DDD so he wouldn't have been there to worry about the LW or Sora.