Because playing a "white" race card will not get him free sympathy, knee-jerk support from blacks, mindless donk votes, white guilt support from communist progressives, reverse discrimination "affirmative" action, etc.
In other words he would actually have to be productive and astute instead of drifting with the current like Rhambo's dead fish.
Little bammy only knows three things;
vote present,
blame Bush,
"I am one of Holder's people and I am just like you."
He can not do anything but play off on his half-dark side. Right now his practical and social education level is about 6th - 7th grade.
.