[Pointing a firearm at people not attacking you is not covered in any "stand your ground" law.
Wrong.
Put down the pipe, man. Meth is bad for you. You can't accost "protesters" with a firearm and be "standing your ground." I don't know how you could possibly see it otherwise, except for the meth you are obviously smoking.
You don't know WTF you're posin about.
Missouri's SYG and Castle Doctrine laws allow a person to use lethal force to defend themselves from a threat wherever they have a right to be.
These people certainly had a right to be on their own property, and the attackers didn't.
So, they had a right to defend themselves against the attackers, up to using lethal force.
If you want to play semantic games like a liberal, "protestors" protest in permitted public areas.
Attackers kick down a gate and come onto people's private property.
This is a dead end for the prosecutor.
