(My bad, that's "collect" the banned firearms).

Very preliminary, this evidently is simply floating the concept to see what the response is. But apparently the Canadian government wants to distance itself from the ugly facts on the ground likely to result, and avoid having to place this perhaps unwelcome duty on the police.
So: if this comes to pass Canadian gun owners might expect to see the equivalent of Blackwater or bounty hunters showing up in full tactical-response mode. Who will also have a profit motive to seize collect the firearms, regardless of how recalcitrant the gun owner might be. What could possibly go wrong?