Originally Posted by mr. peasant
It's so that they have the option to bring them back in a sequel if they want to. Same reason why they didn't explicitly kill Destro either. No point committing yourself if you don't have to.
Moreover, Scarlett and the others didn't play a part in the movie. As such, mentioning them would have just confused (new) viewers. It's just something called "conservation of detail".
Ok thanks for the info me peasant.