It's almost impossible to give any answer besides "someone who had a change of heart in the decades since 1968"
Some fringe possibilities:
*Black pro-segregationist who doesn't want to be near white people. This is a stretch because blacks were unfairly treated under segregation which is the main reason they wanted to end it.
*Someone who believed Wallace with withdraw from Vietnam?
*Someone who believed Trump was honest in regards to his economic populism and didn't like that, though it's more likely such a person would be for Nixon I think
*This barely counts but someone who though Wallace referred to the guy from the 1940s.
*An Arkansan who really liked Bill Clinton and really disliked anyone who dislikes Bill Clinton. Disgusted that many of his friends and neighbors would vote for some New Yorker Yankee. Still hates Obama more but it doesn't matter.
That would explain the Clinton 2016 vote (sort of - but Clinton moved to New York and was a fellow 'New York Yankee' by then), but what about the Biden vote? (Trump wouldn't really be thought of as a 'New York Yankee' but as a populist who wanted to help rural voters, which is why Trump improved so much across rural and exurban regions.)
