I think if Payne had been fit, Christie would not be there. He would be the first name gone if Payne was fit for sure. I think Rory would also be gone if Killen was fit as well giving Ricki something close to a WC squad (and consider Howieson and Keat in the mix) but that's probably the strongest available really. Who else do you go to outside of Payne, Killen, Keat, Howieson, Butler... Bright? Nope. Fitzgerald? (we know that's not happening) That's all there is.
He has picked the strongest squad he possibly could with the exception of conjecture around Christie for perhaps Keat, Butler or Howieson.