Canada

maybe I’m mistaken, but I believe the reason this guy is not being punished for what he did is not because what he did is not an actual crime (as far as I know, it still is) but because police are simply declining to prosecute it in this particular case.

You are, indeed, mistaken.

Self-defence is not a crime in Canada. If you're starting from the position that it is, you're wrong, and you need to educate yourself more on how Canadian law works.

Section 34, Canadian Criminal Code:

34 (1) A person is not guilty of an offence if

(a) they believe on reasonable grounds that force is being used against them or another person or that a threat of force is being made against them or another person;

(b) the act that constitutes the offence is committed for the purpose of defending or protecting themselves or the other person from that use or threat of force; and

(c) the act committed is reasonable in the circumstances.

What the police did in this situation is they looked at the evidence, said "This isn't clear cut enough for us to make a judgement call, so we'll leave that to the courts." And the Crown looked at all of the evidence, and made the judgement call that he was innocent. That's how law works. Sooner or later someone has to make a call. Whether that's the cops, or the prosecutors, or the jury, you cannot ever have a legal code that is so thorough in its detail that no judgement calls are ever required. That's why courts and the adversarial justice system exist.

And this particularly case was not even remotely a clear cut one. No amount of detail in the law would have prevented this from being messy and complicated. But when you refuse to look at the details, and just consume only the briefest headline version - "man charged for defending himself from attacker with crossbow" - it's always going to sound easy, because you're not looking at the reality, just an oversimplified caricature of it.