ok I actually wanted to look up what antisematism actually means since the only context I've seen it is israel, so I looked up what sematism is which lead me to one who has sematic qualities which is:
Semitic
of, relating to, or constituting a subfamily of the Afro-Asiatic language family that includes Hebrew, Aramaic, Arabic, and Amharic
Saudi Arabia is arabic so technically they're correct?
"semitic" has this broader meaning, yes, but the specific term "antisemitism" is only used to refer to Jews, not to Arabs (or, for that matter, Amharic-speaking Ethiopians).
It also doesn't specifically refer to the State of Israel, but to Jews everywhere.
Similar to other racial categories these do not have a real link to reality, and are mostly artifacts of how racist tried to link these to something tangible (Think how White is applied to a specific subset of people with pale skin)