It's a difficult argument to make, in the same way it's hard to argue against calling all anti-trans activists "TERFs" despite the fact that many (most?) of them are right-wing agitators and not in any way "radical" or "feminist".
But I would like to avoid muddling terminology around "zionist" because there are a lot of people who aren't actually zionists being called "zionist" because they are Jewish or express sadness over the suffering of Israeli citizens while still supporting Palestine.