Well he's not in a workplace. He's a child, in a school, and entitled to an education.
I'm a teacher. I don't understand all this bullshit about uniform. I think uniforms are a great idea, if they're practical. As it is, I watch children every day operate heavy machinery/cook/draw and write creatively wearing shirts (buttoned up to the top) and ties. Ties ffs! In a workshop!
And then schools just have to go and take it a bit further, often claiming that uniforms help children to prepare for the workplace. Because it's a difficult thing to learn, y'know - wear a tie to work. 
What this comes down to, as unfortunately is the case with many English schools today, is marketing. Look how smart our children look! That MUST mean we're doing a good job. Look, OFSTED! They're wearing blazers! God forbid they should get a 'chavvy' haircut like those working class children.
I'm speaking from experience when I say that black/working class children are disproportionately affected by these ridiculous, pointless rules. The 'education' children receive in exclusion is NOT good enough to make up for time they lose in class. I've seen some very vulnerable children punished this way and it makes me very, very angry.
This is what comes of schools that are more interested in outward appearances than they are in children's wellbeing and learning. The best school I ever worked in had a lax uniform code; children came in with their hair dyed every colour under the sun. On one memorable occasion one of my clever, funny, hardworking top set boys came in with neon pink hair. The ethos was inclusive and warm, the discipline was the best I've ever seen and the children were heavily involved in various activities in the local community. The school is in the Good Schools Guide and had fantastic results.
These teachers need to find something more important to occupy their time than writing lists of approved haircuts.