There's two dynamics at play here. First is the DUmmies' natural inclination to develop a raging crotch rash at the sight of anyone overtly displaying patriotism or expressing a sense of American spirit and resilience.
The second is, Oklahoma being a red state, they wanted to see their peoples' morale crushed and a groveling admission that they needed the federal government to take their hand and reassure them as if they were frightened children. They want to see crying people sobbing, "Where is FEMA? Why isn't anyone from the government helping us?", so they could dance on their misery and snark loud and long about how the "tea baggers" are suddenly crying out for Uncle Sam.
Flying the flag as a way to say, "We're still here, and our spirit is not broken!" galls them to no end.