I think the core point is addressed: Based on the ruling, a teacher calling someone's son "Ma'am" should also be protected speech. The ruling makes no judgement

I think the core point is addressed: Based on the ruling, a teacher calling someone's son "Ma'am" should also be protected speech. The ruling makes no judgement on what the student can say, as the student is not an employee of the college. I would imagine that the college is able to enact consequences to the student's speech, and not run afoul of legal issues, but I am not a lawyer.