That website is reform, but they made a correct statement: In modern times, anti-Semitism is understood to be anti-Jewish activities, but a Semite is not a technical term, and can refer to anyone from the Middle East.
It's a pretty word for Jew-hatred. I don't know who came up with it. We stick with what we have, but the term can be substituted for Jew-hater with no problems. The article is packed with nonsense.