That's a rather uncharitable summary of the contents of the email. The email wasn't saying that white students should be able to wear blackface without feeling

That's a rather uncharitable summary of the contents of the email. The email wasn't saying that white students should be able to wear blackface without feeling uncomfortable - in fact it said the opposite - that social norming (e.g. making people feel uncomfortable for wearing offensive costumes) was the way to deal with the problem, rather than the university dictating what students should/shouldn't wear.