I don't think it's posturing at all. I don't believe he understands or cares what the impact of the tariff will be on either side, he just thinks tariff is "the most beautiful word in the dictionary". He continually re-iterates that Americans won't bear the cost, that the cost lands on the exporters somehow. There's not much upfront cost to imposing it, he does not have to build a tariff, and with a fully Republican government he will have few obstacles to making it happen. He has specifically picked a cabinet that will do what he wants and will not push back on bad ideas