Forgive me for asking, but what is a “cornball brother”? I don’t think I’ve come across that before.
Maybe he confused him with Cornbread Maxwell.
I had not herd it either, but you can read about it: http://www.urbandictionary.com/define.php?term=cornball+brother
Cornball is just this particular race baitor’s version of “uncle Tom.”
RG III is simply not toeing the racially correct line.