That’s not an answer to the question.
Interesting that you use the idea that English is a living language to push back against people using a term in a way you’ve decided is incorrect. Seems like you don’t think English is that alive after all if you refuse to incorporate all Semitic people into the concept of antisemitism.
You can’t cite descriptivist arguments to defend your prescriptivist attitude towards the term antisemitism. It betrays your own bias and deflates your argument.
Language evolves, just like you said. Which is why people are realizing the double speak nature of this idea that antisemitism is only when you’re prejudiced against a specific Semitic people group and the others don’t get a term to describe prejudice against them. Your position is an Orwellian attempt to deny a group of people the ability to specifically identify their oppression and it’s sad.
Like you said, language evolves. People are deciding that the definition you follow is very limited and constrains dialogue by being needlessly exclusionary. So they’re seeking to expand the definition to its logical conclusion.
You can throw a fit about other Semitic people being recognized or you can accept that language changes to fit our current understanding of the world.
Antisemitism still refers to prejudice against Jewish people. It’s also being extended to all Semitic people as to disallow them the ability to categorize prejudice against them is to obfuscate and to an extent even deny their own reality.