well, yeah but usually those people shoot back. not like here in the states where it’s stupid rich college kids. can’t mow them down! we don’t want neil young to write another song about it.
In Kosovo, in Bosnia, in Afghanistan, in Iraq, the US military is frequently called on to perform crowd control. Using lethal force in those circumstances would not further the mission objectives.
Over the last few years, the US has done a lot of crowd control in Iraq; it is one of the first and fastest duties to be handed over to Iraqi forces, for pretty obvious reasons. But it's still an important component of the training and equipment.
None of which is an endorsement of this particular engineering approach. I don't know if it will work, but as long as the cost isn't too high, I like to see our military thinking outside the box. It's a toy? So were the wheel, gunpowder, helicopters, and radio-controlled aircraft.