That's not the point. The point is if they wanted could they. And the answer is no. They can try, but they already have with torrents and failed. Torrents moved to random ports and traffic got encrypted. With Bitcoin it's even easier because you're dealing with very tiny amount of data.
If push comes to shove, Bitcoins can be exchanged by sending Email
yeah, that comment was a little off topic, but they could still "try" and i doubt we would ever have to come to that level, atm im trying to find this project i learned about a few weeks ago, it was call ip2p or something, it had a .de domain i think, but i cant find it. It could easily be used for bitcoin if memory serves.
http://en.wikipedia.org/wiki/I2P