In a way it isn't. If someone in B.C. hears the wrong message, they may not go and vote. It's just like saying the GOP won in CA 3 hours before voting time ends and then the people who were going to go out and vote don't go. They can't call it BEFORE everyone votes, that puts some other people right off the track. I'd go anyway but I see the reasoning.
If they want to do this right, they should have the polls close across the country at generally the same time. The way it's being done now clearly has loopholes that people can pick up on. The law was made with good intentions, but this isn't 20 years ago. It works in principle, but it cannot work in application in the internet age.