Oswald's sole purpose was to be a way for the writers to point out the evil that supposedly exists in Jack. i.e., they've both deliberately killed little children, therefore they are somehow kindred spirits and recognize something in each other. personally I think RTD is over-reaching when he goes for these grand concepts.
I think RTD isn't so much over reaching as off his nut. He's completely lost it and has no sense of proportion, or much of anything else.

