Of course, they're not completely out of the woods. The X might not want their DNA, but they may still want the space that they're occupying.
interesting insight on what motivates the X, but wouldn't they just as easily assimilate them just to get them out of the way, then melt and turn into something else later? I guess the X can file that under "We were going to get to it later."
OOH! BURN!! XD