Art is an art, not a science. Even if DPC gave another artist the original models, the new artist would still need to pose them. The blocking, pacing, and composition of the resulting scene would be different than what DPC would have done. In theory that could be mitigated if DPC and the other artist were very familiar with each others styles, but that would take a lot of time to develop - if it ever developed at all.
And that's assuming DPC can convey what he wants the scene to be in the first place. I'm sure DPC has plenty of notes, but I doubt they're in the form of a "shooting" script that could explain when a character is meant to be framed sympathetically, what background details are important or the like. There's no guarantee DPC would be good at conveying that information, especially at first, and we know he's a control freak.
Basically, developing a reliable team is an investment. In the long run it can pay off and allow you to accomplish much larger tasks far more efficiently. But in the short term it actually slows down production as resources have to be devoted into training rather than the product itself. And there's always the risk the team won't pan out and the investment will be wasted; that's a particularly common problem with artistic collaborations. Plus, it requires a whole host of different skills than just working on the project alone, and DPC is clearly not interested in learning those skills.
