just a couple of quick statements.
When I was in High School there were almost no fights with boys or girls and one of the reasons was a rumor that was circulated that there was a group of 7 Varsity football players and wrestlers that would break up any fights and any guy who hit his girl friend would pay an awful price. That group called itself the "Hit Squad" and the rumor was investigated after a bully got his ass kicked by one member for picking on weaker kids.
Was it a real group? Yes but there were only 5 members, and their full member identities was never widely revealed, and no one got in trouble because the Hit Squad were like brothers.
My second observation is that grown men who would stand by during what could be called attempted murder is reprehensible and these "Guards" are worthless.
They should be trained and armed, however the cost would be much higher because of the liability that comes from having armed guards.
I have also found that in places where concealed carry laws are in place like AZ. there are fewer physical altercations because you never know who is and isn't armed. It won't change kids problems but it might embolden adults to get involved more readily if they knew they would be safer if they did.
When I was 20 something and didn't have a wife and kids, I was 10 feet tall and bullet proof. Now that I'm 41 and have 6 kids, a wife and ex-wife to think about, my perspective has changed dramatically.