Had the Met gala opted for an Islamic theme (say, “Arabian Nights: Magic and Islam”), accusations of appropriation would have surely followed. This year Jared Leto, an actor, dressed as Jesus; had he dressed as Muhammad, even if in a plain and historically accurate thobe and turban, he would provoke all manner of disgust and denunciation. One can conjure any number of nightmare scenarios for galas themed around Judaism, blackness or, say, Aztecs — none of whom remain alive to be offended — no matter how sartorially sensitive the dresses.
This has nothing to do with cultural appropriation: you wouldn’t catch a Muslim dressed as Mohammed as it is considered disrespectful in the Muslim culture, and therefore, if another (white, Christian or not) person were to do it, it would be deemed as such.
When you started writing this article, you had a point (or so it seemed when I started reading it), but somewhere along the line, your research fell short, and you failed to deliver.