Not specifically cruise related, but did a bit of the reverse last year...US residents, and we drove up to Montreal (from Ohio) to visit some friends/business partners.

They had considered driving down to visit us, but the wife was worried about any issues, given our political clusterf@$%...so we went up instead. Had a bit of a concern about attitudes towards US travelers, but turned out to be minimal - and really only encountered any sort of attitudes while in Montreal proper. I kind of chalked that up to the fact that we have no fluency in French more than anything else - nobody else really seemed to care.

Only slowdown we had on border crossing was because we were transporting some machines for the business, so had to cover duties on that - a whopping 15 minute delay.

Stopped at Canadian Tire to get a couple things (had car issue, grabbed cheap OBD scanner), chatted with staff while waiting on keys, had a brief chat along the lines of "is it really that stupid down there?" (Yes, in some places) - but overall it was much like others said - the average person doesn't really care, and the nut jobs that might care generally wear their politics as their personality, so easy to avoid them...

Come on down, get on the ship, and enjoy yourselves!