Uncle Tom is a term used by blacks to slander anyone not on the Democrat Party gravy train. If they listen to the NYTimes, they would come up with some other slander like Oreo.
Its about demeaning your opposition, nothing else.
In the late sixties “Uncle Tom” was used to slander any black person who was not an angry militant or disagreed with those who were.
The Chicano movement started up among Hispanics about the same time. They sought a term equally insulting for the nonmilitant among them that rang like “Uncle Tom”, so they came up with “Tio Taco!”