"The response to Hurricane Katrina was a reflection of basic administrative incompetence and cronyism, not active racial animus. Bush made an active effort to court black voters, marginalized (mostly) Islamophobes, he appointed a diverse Cabinet, and, defying the nativists in his own party, he brokered an immigration compromise that policy-wise, was better than anything we're going to see for a very long time. The spate of noose-themed hate crimes during 2006-2007 seemed to make him genuinely angry."
What's more, the RNC chairman under Bush rather explicitly repudiated the party's longtime "Southern strategy" of appealing to white racism as a way to gain votes. There's lots that was wrong with George W. Bush -- I still think he he's in the conversation as one of the worst presidents ever -- but racism, even passive winking racism, wasn't one of his sins.