It is certainly possible; I just said there's no evidence of it that I know of. Whether or not that is the case is immaterial because it's not what Arrington was suggesting.
Because that interpretation makes zero sense in context.
"There are very few minorities here. When they are here, they get hired much more easily than their white or asian counterparts. There is no conscious or subconscious desire to keep minorities out [...] It’s the complete opposite."
He's saying that people consciously desire to hire minorities, so they make it easier for minorities to be hired. There is no reasonable way he was suggesting that underrepresented minorities in the Valley are more competent than everyone else. If that were the case, one wouldn't need to desire to hire underrepresented minorities; you'd just get them as a byproduct of seeking out merit.
Your logic doesn't hold. You're making assumptions about why minorities are sought after (or rather why Mike thinks they are sought after).
If minorities in the valley are people who are above average, then that would make them more desirable in itself. All else being equal, if you got to pick candidates only by race, and you knew (or thought you knew) that one group was above average, it'd be hard not to let it influence you.
And your argument that one wouldn't need to desire to hire them is flawed, because if being a member of a minority in SV actually makes you more likely to be highly skilled, then that is an easy signal for you to seek out the person. You wouldn't need to, but it's human nature to consciously or subconsciously try to take "shortcuts" in evaluating other people, especially when other knowledge of the person in question is lacking.
Can we at least agree that your point is contrived? I've never heard anyone claim that black people in the Valley are more talented than everyone else, so this is a silly argument.