Try to keep current politics out of this. The issue is to what extent if any it would hurt Reagan in 1980, not any more recent comments by any later American president...
My guess is that he would say something like "well, I really only meant people like Idi Amin. I'm sorry if my disgust with brutal dictators like him led me to make what some would consider insensitive jokes about African leaders as a group, which was not my intention. But really, instead of discussing an unfortunate joke of mine made several years ago in what was supposed to be a private conversation, shouldn't we be focusing on the real issues of what is happening to the US under Jimmy Carter?" And yes, I think he gets away with it...