Reading wikipedia, I get a fairly different story. I did a short search for other versions, but mostly just found inaccurate yahoo-answer type sites.
http://en.wikipedia.org/wiki/Lyndon_B._Johnson_Space_Center#...
One of those specifications was the minimum distance between mission control and the launch site. That specification was revised upward so that it just barely excluded the then-leading site after Rice University agreed to donate the land. It doesn't take a Von Braun to figure out what happened.
That politics plays into the decision making process of which site to use isn't too shocking, but Symmetry was claiming that the very creation of that site was political.
NASA denied there was political influence, but it's hard to say since the stars lined up perfectly for them.