If you really want to get into the meat and bones of this argument, then calling someone a bounty/uncle tom/coconut etc is actually a result of white supremacy.
The idea that you can even 'act white' is perpetuated by white supremacy and fuelled by racist stereotypes that black people were expected to conform to.
Thus a black person calling another black person one of those terms has only fallen victim to one of the oldest tools of white supremacy, which is one of the reasons why I say it's not racist. Offensive, insulting? Yes absolutely.
But also the term isn't only used in the context you are trying to say - Rio Ferdinand used it because Ashley Cole decided to stick up for Terry even after he said some racial things against his brother. And in that situation you'd expect someone who can relate to support you, but instead Cole decided not to, therefore Rio called him a fake.
Uncle Tom has been colloqusalised through slang & media, so when somebody says it they're not trying to be ignorant of its *true* meaning.
edit - what on earth is black on black racism? black on black crime doesn't exist, why would black on black racism exist?
There's just racism.