Again, if they really want it they will find a way, just look at what they did to gold, at first fiat was completely backed by gold and then the government began printing more money than the gold they had in stock since at the time the dollar was defined by a weight on gold, in fact the word dollar was a form of weight for gold similar to pounds or kilograms, but they circumvented this by printing more fiat, it is possible that in the future governments get bitcoin and back their fiat with it and then they print more fiat than the bitcoin they have in store.
Bitcoin is completely decentralized, and gold is not, as historically governments keep a lot of gold in reserves, and they can manipulate it somehow. Nevetheless gold price has risen last decades because of printing money. If governments decide to manipulate bitcoin, they will first need to buy it at a significant volume - wich will cause a huge rise in it's price. Not an easy task for them 