You are absolutely right. However, consider now that USA invades Canada as a result of this. This is infinity worse and always unacceptable. Nobody—not even American citizens—would tolerate that.
Two week of 24 hours news with the proper perspective and the people would be asking in the streets for the invasion of Canada.
In fact, some redneck militia trying to invade Canada is a common trope in US entertainment (from South Park over to The West Wing, even a whole movie exists), implying that it would be pretty easy. It's played for laughs, but it adds to the desensitisation of the public opinion about such an endeavour. Consent is manufactured.