This can all be solved by moving the bitcoin network over to a darknet (such as onion or i2p), in which case the government(American) can only block people using those services (which it currently can't do).
No the real target when the authorities want to clamp down on bitcoin will not be the network itself, but the exchanges. It is the exchanges that give bitcoin a lot of it liquidity, and it's exchange value gives people more confidence in it's usage as a currency, right now there are far too few goods and services that can be bought with bitcoin so the exchanges are crucial to it's healthy growth in use.
Shut down the exchanges and you kill bitcoin, it also doesn't help that the exchanges themselves are very vulnerable to authority action.
I think you have a point, but let's remember that the exchanges are more flexible and could be conducted without government restriction elsewhere, right now they're easy to clamp down on because we simply don't need to worry about that yet.