That's not the question I asked you. If it's said by one black person to another, is it racist. Yes or no?
Frankly I don't know. It's a racist word but it's not a person of one race insulting a person of another race. I'd probably say no it's not, there's no question of racial superiority or discrimination. But it's contentious.

We haven't established it is racist. If it were racist for one white person to call another a gammon, then black people calling each other the n-word must be racist too.
Even if I accept a white person saying doesn't have racist intent, that doesn't mean the word isn't racist. I think it's inappropriate for black people to call each other nigga, but I don't think it's racist. There's a difference here though... it's a term of endearment between black people. If we have an example of a black person using the word against another black person to cause shock or distress, then yes that's racism.

I don't think there are simple answers here. Context is important.

I think you're making my argument for me here.
It depends if your argument is it's not racist, or it's just not as bad as other examples of racism. I don't agree with the former, but I do agree with the latter.

Have you ever heard of the book "Uncle Tom's Cabin?"
No. And no I don't think this is racism. It's not a direct reference to skin colour. That's the only reason I find "gammon" racist. Not just because it's only used against white people, but because it refers to skin colour.

Uncle Tom only applies to black people. Same for the n-word. Uncle Tom was only ever used by black people. You therefore must hold that any black person using it was being racist against their own race.
See above. You're misrepresenting my argument.

I don't use racial slurs, but you just said it was a political slur, not a racist one.
I'm acknowledging there's a distinction between slurs used generally against people of a race or ethnicity, and slurs used against people of a political persuasion. It's political because it's reserved for conservatives, but it's still a reference to the skin colour of the people it insults.

The most bemusing part of this whole thing is that they're not objecting to being called an angry ignoramus, they're bitching that it's racist so people who are also white will stop a using a word to depict them as an angry ignoramus.
I think it's a stupid word to use because the people who use it also have a tendency to accuse the people they use it against of being racist. That's pretty amusing to me.

People who get offended by insults like "ignoramus" are snowflakes. But if you're insulted because of your skin colour, you have every right to point out this is unacceptable. It's not a term of endearment like nigga, is it? It's an insult. Insults based on skin colour should not be acceptable, regardless of whether it's black on black, white on white, whatever. Find better insults.