I think it's pretty simple. Caron opted in, hoping that a new staff and system would mean a bigger role for him and since he's not likely to get more than the vet minimum anywhere, it meant he didn't have to pack up and move.
Then after the Kings signed a few wings, he saw the number crunch and was let go and/or asked to be let go so he could catch on elsewhere.
The Kings don't gain any caproom or save any money by waiving him (I don't think) and there are no roster size constraints until the deadline in the preseason.