It seems there is always some carriage contracts concerning new services. Carriage rate vs. potential subscriber base.
The KTLA-SD service has been available for a number of years in Canada. First as a premium service then later included with digital basic service.
I believe since 1992 in Canada. I know that Shaw has only added WGN-HD within the past year or so.
All the CW programs that are aired on Global SD will no doubt be simulcated on KTLA-HD from Global-HD West (Vancouver CHAN, Global BC)
In the eyes of Shaw. They already offer WGN-HD. They would see no need for KTLA-HD as most of the CW programming is already available.