The only reason i can think of is if he comes up and shows he is a good player they will look bad for sending him down from the start. Otherwise for a little cap hit. He is a good player from what i've seen of him.
Here's what happens -- Rangers decide to call Kennedy up, gets put through re-entry waivers... oh, last team place sees the Rangers are trying to call up Tim Kennedy?... Boom, T.K. is a Devil and lights us up. **** that.