Why interpret it as his intention to "lend credibility" to Kwanzaa? Why not interpret it as his desire to acknowledge a Black holiday and thus avoid being called racist--which we know he's sensitivie about? Until the "extolling the virtues" comment made earlier, I really didn't realize how minimally laudatory to Kwanzaa itself the statement actually was. It's more laudatory of Black contributions to society than it is of the holiday.
Well, I guess one could look at it in that respect.