He should also put export tariffs on electricity to lower demand/price of PQ electricity (or subsidize their electricity from tariff proceeds) that is main cost of aluminum production. Buying a strategic reserve of Aluminum will keep factories open, and allow better deals/pricing for “allies” or new friends, or later dumping on US when they end the trade war.
Dairy exports from Canada are very low. If Trump gets to boast that “he singlehandedly saved the US dairy industry” without any retaliation, then its a nothing burger where politics crying over the nothing burger will help distract from all of the other pillaging of America he plans.