I think everyone has been quiet because we are currently allies of both Canada and America. You are in NATO so Article 5 should see NATO support you. Maybe initially Australia would go neutral whilst pressuring America diplomatically. I genuinely believe many Americans would support you.
Also I believe many in the US Defence Force would refuse orders to attack Canada. This would trigger a US Civil war.
Silence speaks volumes. There is no trust in Article 5 for our defence from another NATO member. NATO didn't speak up. Not one person. Europe has already said it's arming for themselves against Russia, we would get peanuts at best. There are no rosy filters here. And there is no American diplomacy.
I fully understand. We don't trust America to ho our our Defence allience with Trump we're we attacked. Most Aussies don't support AUKUS and want to build Defence alliences with others and ditch America.