If anything hints at gang affiliation, schools make you stop.
That hat isn’t special. This is standard in US schools for decades.
Wearing a hat signifying you’re part of a gang, or throwing up gang signs, or doing anything that makes you stand out as a “part of a group” that could threaten school security and safety, they stop it.
I’m not saying I agree with it, but I don’t know of a time in any US state that such a thing would be allowed.
To a school administrator, it’s just another gang.
You’re talking, “If things were fair”.
But this is school, an authoritarian regime.
Districts differ of course, Where I am, “lightweight racism”, KKK references, anti-black, anti-jewish and anti-gay sentiments are given the “tsk tsk” treatment but looked the other way by teachers and staff.
But even here in TrumpLand, a boy came in wearing a MAGA hat in 8th grade and he had to take it off or be sent home with disciplinary action.
So, it’s not “because its California”. It’s “because it’s school”.