Somehow, I doubt this report. Such a weapon system would be highly secret to begin with, not revealed to or through a foreign news media. Second, this kind of low-lethality weapon does not sound like one the USMC would be working on; the Corps is not a crowd-control, constabulary mission type of unit, although the description indicates a possible support use in a defensive position.
But what do I know?
The Marines are the primary force for guarding embassies. That is it’s most likely application.
The US DOD Joint Non-Lethal Weapons Directorate is run by the Marines and is based in Quantico, VA.
And yes they work on things like this. It may be on their website.
I’d have to disagree. The Marine Corps has been doing these types of missions for so long they literally wrote the book on it 80 years ago with the Small Wars manual, and they certainly got plenty of practice in Iraq. Also, I am not sure how much secrecy is needed for a nonle5al crowd control system.