If mining is controlled by government, they are still very limited in what they can do. They still can't reverse transactions without completely damaging the trust which would cause a flight into altcoins. The subsequent fork that would ensue would result in some in the world (who hate the USA) to rewrite the protocol. They are also back into the paradigm of limited money which puts government in a straight jacket of spending and accountability if bitcoin becomes the only currency. If they change the algorithms to include inflation, again it will cause flight into alts...