Find me one explicit quote where Douglas said that the sky was blue. Douglas also joined in Black's dissent in Adamson - that's twice that Black laid out the blanket incorporation doctrine, and twice that Douglas joined him in it. How many times does he have sign his name to Black's doctrine, in effect saying "I agree with Hugo", before you accept that maybe Douglas was okay with the blanket incorporation thing?
That's what I figured. A penumbra formed by emanation.