These aren’t full metal buttons. They’re a hybrid resin and aluminum or copper mix. So less of an issue if it was a full metal button. You can customize it through polishing it desired, e.g., a brushed look, fully polished, raw (as it comes packaged). And yes, your finger oils will add to the end result as well.
He doesn’t understand the nuances of making policy decisions, so his default answer to stuff like this is to just impose tariffs because that’s all he knows. He doesn’t care to understand and would likely eat the crayons you use if you were to try to explain it to him. He’s just incapable of that sort of mental growth.