TBH I doubt the US cares WHAT the Canadians buy - sure it would be good for LM and everyone in the F-35 programme to sell a few more but for the USA it doesn't matter as they will just buy more F-18's instead
In factt here's probably a significant number of US military who would like to see the F-18 programme continued as long as possible - it gives them an alternative, it's lower cost and it keeps the pressure on LM