Drones are no longer confined to military uses. Even in the military context, they won't be used only by the good guys. Like every other component of war, drones will be employed by forces of evil.
The rally wasn't about war or the military but the everyday use of drones to conduct surveillance and even look for speeding motorists. Americans fearful of crime and terrorism have a high tolerance for surveillance, but this is one issue in which the usual rigid left-right, red state-blue state split isn't evident.
Still, in the conflict between security and privacy rights, most people will opt for security. We won't criticize them for that.