It could be a numbers thing with Gabriel. The Kings currently have 14 roster spots filled if you count Holmes, who hasn't signed yet. Therein lies some of the problem. The Kings need to use the little mid-level exception, a tick under 5 mil, to sign Holmes. But in order to get that exception, they have to be over the cap, which they aren't. That means the Kings need to sign another player to use up the money they have left (about 1.5 mil) under the cap, which would also use up a roster spot, taking them to 15 spots filled.
That makes giving one of the few spots left to Gabriel a bit difficult. Now they could cut and stretch Swanigan, which would serve two things. One, it would open up another roster spot, and two, it would increase the amount of money under the cap with which to sign another player. Since my crystal ball is broken, I have no idea what the Kings intentions are, but something should happen fairly soon in order to get the Holmes situation resolved.