That's the problem with the 25%. The CRTC either explicitly or implicitly agreed with the CCTA in the sense that they were worried about predation. They asked how they could deal with this problem and said they could deal with it by forbearance. They said they would slow it down or they would make it very unlikely.
The way you do that is to define a very large geographic region and then say you have to have a 25% market share loss in that very large geographic region, even though in the Wood Buffalo example, Shaw is only in Fort McMurray. To lose my 25%, I have to lose 55% in Fort McMurray. The cable companies don't enter those local forbearance regions all at once; they enter where they have their networks and where the population is.