As I already noted above in a post which has now expired from the quote nest, I don't know if he's using a racial slur or not --- only he does. But how it would help his campaign is an easy question to answer. Race-baiting calls attention to a base he might wish to cultivate, a base that might not be paying close attention, and how has been 'signaled' that there's one of "them" running so they'd better get out and vote.
That's pretty much the point Pogo. When you say you don't know if he meant it as a racial slur, there are shitload of people who are saying, you are among the race consumed, partisan goofballs race-baiting by suggesting it could be to start with. I think you miss how actually common the phrase is and how stupid it makes you look to suggest it has something to do with race.
That's where our politics are now: Take the slightest perceived potential advantage and blow it up by a factor of a thousand.
Then be really, really outraged.
This actually gets us nowhere, of course.
.