I think what your proposed cognitive model of anti-government government workers is missing is something Upton Sinclair pointed at:
"It is difficult to get a man to understand something when his salary depends upon his not understanding it."
I've worked for financial trading companies and for advertisers before, but I can't do that work anymore because I think those industries mainly make the world worse. Not won't do it, but can't. The daily conflict between my principles and my actions would be too painful.
Cognitive dissonance is really uncomfortable. I don't think most people can live with the cognitive dissonance of being an anti-government government worker. Not without falling into what user omegaham correctly identifies as doublethink.
And I think that would be especially true of the libertarians I have known. If I were to generalize about them, I'd say that on average they're unusually thoughtful and unusually principled. Most people don't even try for a coherent political philosophy. I just don't know a lot of people who will think that deeply and then be totally ok not living by those principles.