I don't have the patience or tact to offer thoughtful and gentle explanations (as you did) when it's "pointed out" that many people from the region could be considered Semitic.
It's very much the sort of argument my clever nephew might make. He's a smart kid, but he hasn't gotten to the point where he can understand that a clever fact is not necessarily in any way relevant to a complex problem. And certainly not a devastating argument that can simply stop everyone in their mad mutual desire for destruction.
"Well, shit. We were all Semites the whole time????"