Edit. But to answer your question, some activists in the middle east have some stories to tell you. It doesn't have to be literally cut, state mandated filtering works too. Good luck jamming a HAM radio set.
But an unfriendly government doesn't even need to bother with jamming. A ham (or pirate operator) relaying Internet traffic over radio would be trivially easy to find. It's fairly easy to triangulate the location of a transmitter, especially one constantly keyed up. A government frowning on such activity would just triangulate the transmitter and go arrest the operator. An extremely unfriendly government would just blow up the station, operator and all.
If you want to make some decentralized network go buy some cantennas, leave hams out of it.