Not that I disagree with your broad points but race is such a contradictory concept, I’d like to raise some challenges. I’m not asking these questions as a ‘gotcha’, either (although I do make some claims that contradict your argument), and they’re not necessarily for you to answer alone, although you may have some thoughts, which I’d be glad to hear.

Does the answer change if the identification of whiteness requires accepting a racial hierarchy? Of which self styled white people are at the top?

A personal anecdote: I’ve always been uncomfortable with ticking the ‘white’ box on forms. It’s very existence is to put me into one category and exclude me from others, which might more accurately reflect my origins. I don’t fill in that box on any form any more. Or I put ‘other’ or ‘NA’. Not because I’m not white; to the people asking, I would be. I just reject the category itself. It shouldn’t exist. I see being white as a choice, to agree with the government’s view of who deserves rights and who doesn’t. If I was born twenty years earlier, they’d have another box for me. I’m not letting them include me now, just because they have decided to ‘include’ me by their graciousness.

If white is a political category (as is black, Asian, or any other race), and is not, in fact, based on skin colour, can one be racist against ‘white people’? Stuart Hall calls race a ‘floating signifier’, which is a useful concept.

If so, who does ‘white’ refer to? What is it’s content? Southern Europeans might be white in North Western Europe but not in the US, for example. On the basis of skin colour alone, someone from North Africa might be white, until their interlocutor placed them as African rather than ‘Mediterranean’/Southern European. Someone from Eastern Europe might not be white in North Western Europe but they might be white in North America, depending on their accent. And this turns upside down depending on wars within Europe.

Then, a broader question, can there be hate crime but not racism against white people?

The same wouldn’t naturally apply the other way around even if all racial categories are political. I’m being quite broad here because white people have at one time or another labelled anyone who isn’t ‘white’ as black and the powers that be are constantly changing who they count as white.

… hatred based on a characteristic a person cannot change, and was born with…

Is whiteness an inherent trait if it’s content changes all the time and depends on location? Fanon argued, ‘to be rich is to be white, to be white is to be rich’. Revolutionary organising means working, from the beginning, to abolish whiteness; it cannot survive a revolution because capitalism is racial capitalism. As soon as someone recognises the need for revolution they must at once recognise the need for and begin to undermine the category of whiteness.

From this perspective, I can see how one could commit (racially motivated) hate crimes against white people, but is it racist in the same way as it is to be racist against ‘other races’?

I have two questions about the Castro quote. First, does ‘American people’ not include several ‘races’? Second, is it a problem to equate ‘American people’ with white people? Then, for the Che quote, is it not an injustice to show support for the concept of a white race, given that it is inseparable from white supremacy?

(I’m not saying white people should be oppressed, I’m saying revolutionaries must seek to abolish whiteness. I’m unsure if it really means anything to say that white people ‘should be oppressed’ because as soon as that becomes a possibility, there would be no such thing as whiteness, which requires a hierarchy of which it is at the top.)