A quote from the article, about halfway down:
"Pryce, suffering from paranoia, pointed a pellet gun at police, who fired back at him in response."
More generally, police may sometimes be a bit trigger happy, but if you brandish what looks like an illegal gun when they are interacting with you (this is Canada, where many handguns are illegal or restricted), they may perceive a threat and react with deadly force.
It seems that bad guys pointing a fake gun at a cop or an armed citizen is a kin to trying to pet a grizzly bear. It might look like a good idea at first, but in the end the stupid are removed from the gene pool.
Okay. They responded to someone pointing a weapon at them. They get to shoot first and ask questions after. What do you think would happen to you if you did that?