The commerce secretary has in this case a huge conflict of interest in pushing for these illegal policies in the first place

The commerce secretary wasn't the one pushing for them in the first place. The president was.

I mean, look, there's plenty of conflicts of interest, and stuff that sure looks like graft, and claims of people making insane amounts of money off of stuff. But in this case, the commerce secretary's options were 1) do the tariffs or 2) get fired. Minion? Sure. Minion without the self-respect or ethics to quit when they were being told to do unconstitutional stuff? Also sure. Pushing these policies, as though they had agency in the matter? No.