The trespass was because the the mask bullshit. Why are you being pedantic
The trespass was because she did not follow the rules for access to a restricted area - wearing a mask. If the rule was that she had to wear a school uniform, and she did not, then the school can have that student removed. Yes, they should use other means and escalate, but ultimately, it comes down to does the school have the legal authority to require students dress and behave in certain manners vs a student’s right of expression.
Since SCOTUS has never directly ruled on school dress codes, it is still a grey area.
It likes to read it’s responses….this will be the neverending story….