Government can spend a few dozen millions (pocket money) a year into flooding and spamming and otherwise hampering tor (attack exit nodes and bridges).
Hard fork Tor, problem solved. One of the main points of a distributed network is that they are so damn hard to "flood, spam or otherwise hamper"
Attack all high profile users of BTC via a variety of legislative and other measures.
As of now they don't just care enough to do that. But they could if they wanted.
Just like the drug war! Oh yeah, how's that going?
