I think it's a bit more complex than that: free trade is almost always better for the US overall. Sometimes the US does not engage in it for political reasons

I think it's a bit more complex than that: free trade is almost always better for the US overall. Sometimes the US does not engage in it for political reasons (including corruption which is what this seems to be). But yes, self interest is ultimately the motivating factor unless a narrow group can hijack that and hard US interests for (for instance) corporate interests...