Bogus arguments
I get the feeling Iris's and Regina's arguments against the Lil Wayne costume were supposed to make us "really think" about the situation and see why it was so hurtful. The problem is, neither one stands up to any scrutiny.
Regina makes a comparison to someone who dresses up as some gross stereotype of a Latino and calls it a costume. But Mingo wasn't dressing up as a gross stereotype of a black person. He was - accurately - dressing up as a specific celebrity who actually does present himself that way. There was nothing mean or gratuitous about it to suggest he was mocking black people in general.
Iris shares the cruel things she's experienced around campus: the Confederate flag, etc. The person who did that clearly meant her harm, and she has every right to be offended and report them to the proper authorities. But how does that give her the right to take it out on someone who DIDN'T mean her any harm - as you can clearly tell every time Mingo talks about it?
You can see they kind of tried to be fair to both sides, but in the end... really shallow reasoning.