I do agree that the US military's perceived preeminence has taken a big blow, but what you're saying is just outrageously false.
Neither of those latter countries had a large shared land border with the US and ethnically similar populations that would make it easy to attack unhardened infrastructure.
Ignore the article itself; the authors do their best to pretend that the results don't say what they actually say. Look at the spreadsheet with the actual results. Q1 asks "What actions would you take, if any, to fight to defend Canada against a military attack and invasion or occupation of this country by a hostile foreign power? Select all that apply." Of the nine named choices including attend rallies and volunteer for civil defense, 12.2% would volunteer to join the military, and 10.5% would report when conscripted. 28.3% would do *none of the offered options*.
Q5 asks "If Canada were defeated and occupied by another country, which actions would you be willing to take to fight to defend Canada at that point? Select all that apply." 14.5% say they would violently resist, 14.1% would engage in "cyberwarfare" and sabotage, and 38% would engage in nonviolent resistance (protests and rallies). *48% would do none of these options*.
Q6 asks "Would you be willing to make the ultimate sacrifice for Canada and die defending this country against a foreign military attack or occupation?" Yes, 15.5%. *No, 47.5%*. Maybe, 21.6%. I don't know, 15.4%.
Iraq or Afghanistan are not applicable here. Islam permits and encourages suicide bombings in a way that Christianity does not. Further, don't make me laugh about the typical Toronto Redditor soyboi <https://i.kym-cdn.com/photos/images/original/001/330/806/8fc...>'s ability to do anything with a weapon. As said in another discussion of the above survey, "The LARPing from urbanites fantasizing about sniping and droning an invading army is the most cringe thing I've ever seen. Fuckin bugmen, every single one of them".
Also bear in mind that the survey did not identify the invading country, so the results are affected by people having in mind the likes of Russia or China. Even setting aside Trump explicitly ruling out invasion, a US annexation that would result in Canadians electing representatives to go to Washington, not Ottawa, would result in correspondingly smaller percentages for those willing to join the military, give up their lives, etc. As another Redditor put it, the first time Canadians would notice a difference in their lives is when they vote for said representatives.
I would add, or when they realize they can move to anywhere in the US tomorrow. Or when they realize they no longer as snowbirds have to follow the 180-day rule. Or they can apply to any US company's jobs. Or when they can sell to any US customer with zero tariffs, and fewer rules/taxes than to sell to another province today. Or when their USPS (formerly Canada Post) mailman starts delivering on Saturdays. Or when they get access to Hulu and to the US Netflix catalog. Etc., etc.