Can someone who knows about Canadian law quickly say if suicide is legal there and sodium nitrite is legal, why was Kenneth Law arrested for selling

He is selling it online across the planet and it's illegal or at least regulated in many countries outside Canada. You can assist someone with suicide in Canada. You can't kill people because you decide the person's life should cease. He claims his innocence. There are many open questions at this point. But, Canadian law does not extend to the UK and the USA where some deaths have occurred because of a purchase from his website.