If they do that, they'd better hope that no one in Tampa, outside the Republican Convention has a medical emergency and dies because of their stunt. Couldn't they be charged with a felony, at least manslaughter, if their actions caused a delay in getting medical help to someone?
Using unlicensed transmitters (jamming) can cost you $10,000 a day in fines and jail time for each transmitter used. Doing it on emergency services frequencies ought to bump it up a notch from an FCC beef to DHS "domestic terrorism" even without actual disruption and resultant injury or death. If such disruptions were to cause injury or death criminal prosecutions should indeed be pursued against the organizers of the mob actions. These fools are just asking for a "get into GITMO free" card.
FYI:
Manslaughter is a distinct crime and is not considered a lesser degree of murder. The essential distinction between the two offenses is that malice aforethought must be present for murder, whereas it must be absent for manslaughter. Given the scenario of premeditated disruption of services, I doubt that a prosecutor would even consider anything less than murder.
Regards,
GtG