Navigating feelings and manners

The school line was rowdy this morning. The little girl who does not speak english yet compensates by pelting her classmates in the head, and this morning she had a lot to say. The effect trickled down the line and unrest had set in. Most mornings the teachers are out early enough to keep their lines in check but morning conferences have kept them late this week.
Oliver has a hard time standing in line to begin with and most mornings we stand back, wait for his calm bestie to show up so they can brace the day ahead together.

This morning we were early, Oliver grabbed his bags and moved up the line by himself. As the unrest kept trickling down the line I could see the discomfort growing in his body. I called him back: "why don't you come and stand in the back while we wait?" He was more than happy to comply and headed back. Well, current last place in line was held by the boy with his arm in a cast. Broken arm on second day of school. The boy who is very touchy feely, has a hard time with personal space, and apparently has already been called to the principal's office.
This is also the child that I scared off the school ground on second week of school, ran screaming trying to find his parents - proud moment!

Oliver took one look at him and loudly exclaimed, well within earshot of the boy himself and his dad standing with him:" OH NO, NOT THAT BOY!!"

I am sure that boy is just trying to find his place like everyone else, dealing with the same overwhelmed feelings, trying to reach out and in his 5-year-old awkwardness coming across a little wrong. Oliver has played with him at recess and called him his friend. Oliver has also witnessed him getting in trouble. We have given the speech about being friendly with everyone but stay your own ground, and don't get in trouble yourself!
Oliver probably looked at him and either was not up for being constantly touched and shoved, or he associates him with trouble, I don't know. He was expressing how he was feeling. Unfortunately, the 5-year-old is not sophisticated enough to do it in a quiet voice. After gathering him close to me, I hissed - mortified - "you don't have to be rude about it!" That was all the place and time allowed for. He leaned closer and said quietly: "ok, mommy!"

I sent my boy to school to learn to read and write, I was not prepared to teach him how to navigate social norms and expectations quite yet. I can hardly navigate this stuff myself and sometimes I feel like I am "shooting from the hip", making things up as they come along.

God, I hope I don't screw this up!!