Well, he's saying that minds aren't actually biased, but may make judgments that seem biased in certain environments.

I'm guessing that if "certain environments" are significant enough to the survival of the brain, the claim that the brain is biased will still be valid.

I wouldn't be surprised at all if it turns out that biases are in fact moving targets; human brains may have mechanisms for correcting for biases over periods of time that are slower than the current rate of change, but much faster than evolution (say, on the order of generations).