if he wants to arrest netanyahu, he should recognize palestine first. it wouldn't resolve all of the issues, but in order to accept the argument that a crime occurred in the "state of palestine", you have to acknowledge a state of palestine, first.
there is obviously no actual state of palestine, there never has been and there probably never will be. the region was a part of the ottoman province of syria before the british mandate, going back centuries. palestine was what the romans called the region, after the biblical philistines; they renamed in a purposeful act of genocide. the arabs kept the roman name for a while, but reverted to calling the region syria, after the (christian) assyrians. the british resurrected the name out of old italian history books. it had been out of use for centuries.
so, there's a good reason that canada doesn't accept the existence of the state of palestine. but, you have to reverse that if you want to talk about the icc's jurisdiction over a region that you don't accept even exists.
that puts aside the merits of the warrant, which i think are beyond weak. i'm just talking about jurisdiction. the canadian government is operating in a contradiction where it wants to enforce what it calls international law, in a way that is inconsistent from it's own policy because this in actual truth is very shaky in terms of the scope of international law in the first place.
a country like russia, which does recognize palestine as a state (even though it obviously isn't one), would at least be consistent in arresting netanyahu for war crimes, despite not being a signatory to the icc.
if we have to make a choice, i think we should make the other choice: canada should more loudly articulate the position that it doesn't recognize the state of palestine and, as such, cannot recognize the jurisdiction of the icc over a state it doesn't recognize exists.