Oswald in the doorway: the blog of the Oswald Innocence Campaign, by Ralph Cinque

This is Backes' stupid collage, but why, if that is a black man's arm going up, with his sleeve rolled up to his elbow, would the black and white "color" of his skin and his shirt match each other and Doorman's shirt? 

Shouldn't there be some visible contrast between the three? Look at the skin of the black man's face. You see how it looks. So, why wouldn't the skin of his forearm match that? Why does the skin of his forearm match the shirt instead of his skin elsewhere?