Sigh. Software Defined Radio has nothing to do with whether broadcast is required or not. The GNU people are nutters.
With the internet, everyone can transmit, because the fundamental architecture atleast has some control over denial of service. Routability is NOT a scare resource that needs a gatekeeper on wired networks. The only reason firewalls exist is bad application code, which leads to intrusions, and zombie clients in DDoS storm attacks.
With broadcast on EM frequencies, there is no way to prevent people from conflicting over who owns a channel. You see the start of this today with people who own cell phone jammers. Does Stallman think that everyone will decide to run the same software, using the same algorithms, and not fight over channels by upping their signal strength? The only way this system won't lead to chaos is if everyone runs the same protocol and all agrees to be nice.
What would he say to the rich guy who decides to broadcast his data (whether they like it or not) to everyone in town by using a 50,000 watt transmitter/jammer?
This people don't seem to understand that whether something can be centralized or decentralized is entirely dependant on the underlying properties of the resource in question.