In my personal, non-GM opinion as a player, I think telling someone "don't let it offend you" is as useful as telling someone who's just stepped on a Lego with bare feet to "don't let it dig into your foot". Emotional pain is just as real as physical pain; you can choose to react to it in constructive or destructive ways, but telling someone that they shouldn't have felt it in the first place doesn't actually help anything, and puts the onus on the target rather than the initial cause of the issue.