It's not that they forget. You're giving them too much credit. The reality is that being against many of the actions of a country is normal. People like Americans, like American movies, but are against many of the actions taken by the US military, the NSA, etc. People like Indians, but are against the actions of the Modi government. If you advocate against the policies of other governments you can get results. Your country can scale down its cooperation with them, or pressure them, or whatever. There's always going to be some hatred of the country, hatred of the people of that country, hatred of the religion of the people of that country mixed in when the policies of any country are criticized. But, a reasonable person can focus on the main message.

By playing the "antisemitism" card, the Israelis who use it hope to insulate Israel from these normal kinds of criticisms. It's really the only country that gets to play that kind of card, because it's the only country founded in the immediate aftermath of a genocide, by the survivors of that genocide, and is the only place where Jews are a majority. They also get to pretend that any decision other than supporting Israel in everything it does is supporting the next genocide against Jews. The reality is that many of Israel's actions are likely to encourage the next attempted genocide against Jews.