I don't think the Guard would follow such an order (One or two 'tards in the line might, privates can be pretty stupid) but I doubt any NCO or company grade officer is witless enough to not think about the consequences to him personally and how fast he'd get thrown under the bus if he did follow it.
Then there's just the 'Wow that's a really bad idea' aspect to firing on a bunch of heavily-armed pissed-off people who vastly outnumber you from the git-go.
I hope so but recent police actions have dampened my optimism. Now police and NG are two different things but with so many police abridging our God Given and Constitutionally protected rights and claiming they "We're just following orders." gives me little hope on that. I know where 90%+ of the police come down. My hope is that there are more decent and civilized people in the NG and they would not follow an order such as that.
On an end note, I have no problem, none, with every DUmmy to have a horrible, long and painful death.
The question of the police has been answered, an overwhelming number would follow that order.