It's Nym's pseudo-conspiracy theory that the Bradley Effect was invented to discourage black people from running for office. Wilder won, but underpolled.
Now I don't believe in the "conspiracy theory", but the fact that Wilder managed to win has nothing to do with the theory behind it. The mere fact the he underpolled...assuming that was due to race...could be enough to scare parties enough to refrain from nominating black candidates, in theory.
As a non-related comparison, which of the following polls is better? (final result is Smith +2)
A: Smith +20
B: opponent +2
By your logic, Poll A must be more accurate, because it correctly predicted the winner.