Tarrifs are only a positive in cases where they are conditioned on labor, environmental, and other externalities being priced in and regional subsidies being countered. That seems like the case here.
But I suspect that the threat is being used as a negotiation tactic and China will call the bluff.
You're defining "work" as Chinese manufactured EVs having less market share. But if that means everyone that buys pays more for an EV and fewer EVs are sold, did it result in the most benefit for American citizens? What about the rest of the world's population, in which situation is the net benefit greater?