Hmm well really it has to as he is half Dalek whenever we've seen him! I'm not totally sure on the back history, I can't remember if he invented them or not, but he's certainly the person who's pivotal in their swathe of destruction accross the universe, so I can't see much point in including him, unless perhaps they could find him at an earlier stage (before he did the whole Dalek thing) just being a regular evil genius and homicidal maniac :D
He might also be included within the whole intelectual property issue of the Dalek's too.