Board Thread:Questions and Answers/@comment-24326953-20140922231323/@comment-24058209-20140926015411

Well... look at it this way, back in Target: April O Neil, they were told to kill April, but instead the Kraang's Metalhead turned on Karai to capture April... so the Kraang have their own motives in all cases... my guess is that they would have claimed the turtles died in the lair invasion but they captured Splinter - who they probably know Shredder's real feud stems from, or at the very least, they only cared about enacting their own revenge and figured the rat alone would be compensation enough.