I assume I am very out of touch with antisemitism since I have always lived in countries where I assume there aren't very many Jewish people, and I never hear much about them.
I understand that there was a lot of really terrible antisemitism for a very long period of history, and I read and hear that there is some amount of trying to pretend that never happened, which must make it even harder to deal with.
However, I think a lot of the criticism of Israel's policy and actions is probably unrelated to the fact that the people are Jewish. A lot of criticism of the most actions by Israel in Palestine is from the US and Europe, and there is also a history of animosity towards Islam in these places.
Also, there's a chance that a lot of people are clueless about classic antisemitic metaphors. I certainly am. I might have heard parasite used in that context, but I'm not certain I would have thought of it if I was trying to make a similar point to the GP's (about a small nation's relationship to a larger one).
Anyway, not sure whether this post will help anything, but just opening up my thoughts in case they help.