Thank you, great article. I'm Irish, and I have spent much of my life loathing (some) Irish stereotypes, so I can relate to your friend's thoughts. I don't believe rebellion against one's own tribe equates to self loathing. If I were Russian, I would vow never to drink vodka or hang out with all-male groups. If I were Afghani, I would vow to shun patriarch thinking and strive to respect women as equals.
I look white, and I despise white supremacist groups - hate them for their low rent, low IQ, poverty trap thinking. That is not self loathing, it's self preservation, where some people who look like me are behaving in regrettable ways that must not rub off on me. It's like saying "you may look like me but we are not the same - I'm planning to be better than you".