Why did ali call frazier an uncle tom?

Muhammad Ali called Joe Frazier an "Uncle Tom" to express his frustration and anger towards Frazier for what he perceived as a lack of support in the Civil Rights Movement. Ali believed that Frazier's willingness to align with the establishment and participate in the boxing promotions, which Ali viewed as exploitative, made him a traitor to their shared racial identity. This derogatory term reflected Ali's broader critique of those he felt compromised their principles for personal gain. Their rivalry was not just about boxing but also intertwined with the social and political issues of their time.