Good luck with the FCC. I've worked with towers for a few years now, and haven't really had many "encouraging", or even informational, conversations with them. The FAA is another matter, but that's not the issue here.
I agree that I don't think you can require free space for public safety. However, thanks to Homeland Security, public safety access is now more of a concern. When we had a tower provider with a somewhat controversial tower that we had no intention of supporting, they were smart enough to get the local Sheriff's Office on board with possible access and that was enough to get it approved. In addition, Florida initially proposed legislation requiring jurisdictions to automatically approve any proposed towers if they were to be used in any way for public safety purposes. After an uproar, that was toned down but is still a strong selling point for a tower location in the state.
Finally, we changed the local code to allow providers who agree to provide a public service to go higher than commercial-only towers (as long as aviation concerns are met), so it is in their best interest to provide a public safety antenna.