Keitzman and those agreeing with him are embarrassing themselves.
First, I'm not sure why it matters whether our QB is white. Besides being slightly racist, you are overlooking the fact that the changeover from Snyder's big-arm gunslinger offense (Watson, Straw, May) to the option offense (Ell, Bishop) occurred while Matt Miller was QB. Miller was pretty nimble. (And, did we win more in 1998 than in 1995 because of the change in offense, or because of the all-around higher talent level throughout the team? I'd say it's probably the talent.)
Also, you're apparently forgetting that Snyder (and Bobby Stoops at OU) won in their early years with passing offenses rather than running offenses. Snyder knows how to run different types of offenses effectively. (Or, he certainly knew this at one time.)
OTOH, if it turns out Carson is simply a bad QB for any style, then this is a fatal problem for the season. But, I guess I don't know that this fact has been established.