Ok, so Mannix realizes that he will be excluded from some of the privileges of white supremacy but not all of them. So that does kinda start to formulate why he has a change of heart and works with my suggestion.

Somewhat related: When Mannix reads the Abe letter at the end he refers to the last line and says 'nice touch'. He says that with admiration just like Russell's character did earlier....but this time it's in the context that he knows it's a fake. So this is Mannix acknowledging Sam Jack's character's ability to navigate white supremacy and giving him props for doing it successfully.

A good test.....If there's any truth to my idea than the lyrics of the song she sings should show something like that. i'll try to find them.