I think you have very much misunderstood his point. He's not saying that Jews are unique in being able to hide their ethnicity, nor unique in benefiting when we do so. What he's saying that the attitude to that from outside is often different for Jews. If a mixed race person can pass as white and chooses to do so, it's generally acknowledged (especially by the progressive left, which is the point of view the book is written from) that this is a bad thing because they should not have to hide their race in order to be treated decently.
With Jews the attitude has been much more "well what's the problem you can pass as white so you're fine".
Regarding Zionism, two things. First...
Imagine I was taking to someone from a Shia Muslim background. Let's say they mentioned racism and how religion and culture were somewhat intertwined. And I've responded "well black people also have racism. And what about 9/11 that was pretty bad. Did you know about the slavery in Saudi Arabia, also the Taleban are trying to wipe out an other religions in Afghanistan".
None of those things is wrong. Acknowledging them isn't inherently racist. But you'd sure as heck give me the side eye for that response. And that's not all that far from your response.
Think about it. I'm telling your your response was a bit weird and you are essentially pointing out it wasn't factually incorrect. You are arguing a different point.
As for Zionism, I think you are muddled about it. Many consider the state of Israel to be a colossal act of Zionism. Are you arguing that Jews were in more danger from 1948 onwards than before? That seems a stretch to me, frankly. If you want to argue that the settlers are armed thugs who all ought to be in prison, are making life worse for everyone, ought to be in prison and it's deranged they've been supported by the army for decades, you won't find disagreement here, but again, why did you bring it up?
As for religion. Like I said religion ethnicity and culture are not cleanly separable. It's a bad road to go down where done religions get special laws and freedoms not afforded to others and I am against that. But not protecting religion leads to absurdities. Consider the alternative.
Let's say I could be refused service for being an observant Jew, but not an ethnic one. Well how would anyone know? Would it be ok to refuse me service if they say me leaving a shul? But the thing is I am an atheist might well be seen leaving one after, say, a bar mitzvah. Yes that's a religious service, but to not go would be to renounce a large part of my culture and stick a huge middle finger up to my family.
Or if you prefer a non Jewish example, what about a attending a church wedding? That's a religious ceremony too.
If you allow free discrimination based on religious worship or gets utterly absurd and yet people have discriminated so protections are needed.
As always it's a fine line and they're are always edge cases and what you hear about will be 90% arseholes, because basically laws are for arseholes more or less. But just because something is hard and impossible to get right didn't mean that bit doing it is more wrong