In answer to Dr. Pestritto’s question, I don’t think that Scalia is avoiding endorsing the Declaration. It appears more likely that Scalia is bowing out of joining Justice Thomas’s comments which precede Section I. It is here that Thomas quotes extensively from Frederick Douglas, and speaks with passion about how he "believe[s] blacks can achieve in every avenue of American life without the meddling of university administrators." My sense is that Scalia thought that these words were uniquely Justice Thomas’s, and that they stand on their own.
It is also worth noting that Thomas’s last paragraph, in which he mentions without quoting the Declaration and quotes from Justice Harlan’s ringing dissent in Plessy v. Ferguson, bears striking resemblance to Scalia’s concurrence in Adarand v. Pena, in which he states, "[i]n the eyes of government, we are just one race here. It is American." Given this similarity, I don’t think it is out of disagreement that Scalia joins only I-VII, but out of respect for Thomas’s desire to speak about the capacity for black achievement.