He shouldn't have to make apologies for non-issues. We really don't want our politicians having to publicly respond to every accusation that they said or did something mean at school. Many of his comments in adult public life are support enough that he is not an overly compassionate man. Everybody does things in their youth that seem stupid and offensive years later. Making embarrassing public apologies for actions in one's childhood, and consequently legitimizing the political importance of the accusations to the political debate could be seen as incredibly weak by many voters. It doesn't matter how he responded to these accusations, because these accusations add nothing to the debate.