It all looks very similar to the discussions around the Black Lives Matter movement. A common reaction to that slogan was that, well, all lives matter, and therefore black lives matter by extension, so why even emphasize the color of lives, as if it makes them matter more. This reaction was widely condemned as insensitive, inflammatory and racist, but I am having the same reaction when looking at this working definition.
There are certain words that have been abused to the extent that they now cause knee-jerk reaction in the audience. Words such as racist, sexist, nazi, fascist, and so on. Antisemite is one such word. We might make "demonizing, or stereotypical allegations" about the Iranians, or the Chinese, or the North Koreans, or the Russians, or the Americans, as well as "hold them collectively responsible for actions" of their govenrment — but we do not have a label for this kind of speech that will tarnish the reputation of the speaker as much as the word antisemite or racist does. And it feels wrong somehow.