If you look at LRAD's product guide [1], they primarily describe their devices as being for "communication", not as a weapon. Now, they apparently can also output "deterrent tones", which are potentially dangerous - and I wouldn't be surprised if the product guide 'sugarcoats' things by focusing on non-offensive use cases. But it seems like a leap to claim that it's incapable of being used safely as a loudspeaker (which seems to have been the police's intent in the DC march).
That device is indeed for "communication" in the same way that a warning shot is a method of communication. This is not hyperbole, this is quite literally what the device was designed for, per the US military itself:
"AHD is a non-lethal, counterpersonnel, long-range hailing and warning device capable of producing highly directional sound beams, allowing users to project warning tones and intelligible voice commands beyond small arms engagement range. This capability helps Soldiers more effectively determine the intent of a person, crowd, vessel, or vehicle at a safe distance, potentially deterring them prior to escalating to lethal force." (http://www.pica.army.mil/pmccs/combatmunitions/nonlethalsys/...)
[1] https://www.lradx.com/wp-content/uploads/2016/06/LRAD-Produc...