By purposely posting a picture of a black man CU4 is saying that that makes it different. He is saying, even blacks are opposing Obama now. That automatically puts blacks into a different category. It says blacks are "other", different. It says, see, even those other, different, people over there, who should be backing Obama, are now opposed to Obama. CU4 is the one implying that they aren't supposd to think out of the box, but, hey, isn't that amazing, they are.
BSB