How is Mike Huckabee like Martin Luther King?

Dartmouth's Bruce Sacerdote and Owen Zidar analyze the words used in candidates' speeches. They conclude:

John McCain and Mitt Romney are the most like Ronald Reagan whereas (within the set of primary candidates) the words of Mike Huckabee and Barack Obama are the closest to those of Martin Luther King. Hillary Clinton is by far the candidate closest in oratory to Bill Clinton.