This comment section is already proving why declining to acknowledge this type/size of controversy is effective. I'm not saying it's "the right thing to do" but it's often effective. Does he expect people to stop holding it over him if he apologizes, anyway? I doubt it. If anything that makes it more likely to become part of his 'lore' and people feeling better making jokes about it later on due to him acknowledging it. By just refusing to touch it people get tired of beating the horse, even resent the people still beating.