Its less nuanced than that.
In Trump World, Colin Powell was everything they hate; Harlem born of Jamaican immigrants, a Never Trumper, a defender of Democracy and not white. He was the Jackie Robinson of high US goverment office with the exception of Thurgood Marshall. I can not help but suspect a deep seated racist hatred by Powell's critics. In 1996 Colin said he could no longer be a Republican as the party became more anti diversity.