Trump/Buchanan/WND are using some sort of weird version of a logic problem, as noted by Will.
They’re saying that we don’t have his academic records, but they “heard” he was a bad student, so they’re wondering how he got into Harvard. Occam’s Razor, which tells us that the answer which requires the least amount of suppositions, would handily tell us that he was a good student and those people are full of shit. As opposed to the wack-a-doodle theory involving affirmative action and who knows what else.
It’s like standing near a window and seeing rain everywhere, but not being able to see clouds and demanding proof that there isn’t an army of people with fire hoses spraying the neighborhood.