He has a sound logic for that as well.  America is supposed to be a nation of laws, not of men.  National holidays that honor a particular person encourages a 'cult of personality' type reverence (bordering on worship) of the person, instead of the ideals that he promoted.  We have already seen modern politicos claiming support of his ideals, among ideologically opposed political figures, due to distortions of MLK's intentions.  I've literally seen some people claim that MLK was a marxist at heart, which is complete bs.  And I've seen Glenn Beck functionally claim to be MLK's modern torchbearer, which is equally bs.  I don't doubt that MLK was a personal hero of RP's; he remains a personal hero of just about every adult American seeking any public office.  Which is, itself, an irony; considering that it's a fact that the majority of the people that MLK was protesting were actual local and state officeholders.  Said another way, they were the government.  Personally, I think that MLK would be disgusted to see how his legacy has been used to justify wide abuses of law by governments everywhere, but my opinion on the matter is of no more value than anyone else's.  There is a sound reason that Islam prohibits the construction of images of "The Prophet", even though they tend to go overboard on the matter.