This is a very good question.
I can't comment on this particular event because I don't know all the details. The only thing I can tell you is that in Quebec, police officers are not trained to kill someone in order to save their life. Obviously, when a person is suicidal, it is not the police officer's mandate to kill them to save their life.
On the other hand, it is not the mandate of the police officer to be killed by a person who, unfortunately, has mental health problems. I'm not talking about this particular event because I don't have the details. However, if a police officer arrives at the scene of a call, as happened in the case you mentioned, and a person opens the door with a baseball bat and runs at him, he will still have to defend himself with the tools at his disposal depending on the threat. This is the notion of dangerousness. Do we want this? Do we wish for this? No police officer wants to have to do such a thing.
Unfortunately, we are sometimes called upon to react to an aggression. Are there other tools that could be used? Could these calls be directed to a social worker instead of a police officer? Again, the notion of dangerousness is managed by the police, while the crisis and assistance is managed by health services. If health care workers were sent directly to the scene, they would be exposed to accidents.
Police officers are sometimes faced with situations where they have no choice but to intervene to protect themselves or others from a potential assault by a sick person. In Quebec, fundamentally, a police officer is not trained to kill someone in an attempt to save their life.