It the conservative version of affirmative action (or Confirmative Action), where any semi-conservative black person with an interest in politics is instantly elevated to dream candidate. Because that will show once and for all that Republicans aren't racist. Add to that the fantasy that blacks will have a revelation that their dedication to the Democrat party is all a big mistake, and will vote for a black Republican. For some the dream never dies, so we get people pining for Colin Powell, Condi Rice, J.C. Watts, Herman Cain, and now Ben Carson.
I think you nailed it!