It would already be subject to Title 9, they have to provide equal access. The school can certainly argue that all students have to meet the same requirements

It would already be subject to Title 9, they have to provide equal access. The school can certainly argue that all students have to meet the same requirements to participate, which would hinge on whether the student could reasonably anticipate the consequences here (an example where that isn't possible is if the school created and applied a policy for the incident). My first comment is in response to the people inventing parallels that don't exist at all because schools and work places are very different things and wasn't an attempt to thoroughly examine the specifics. A finding that the existing obligations of the school do apply to this situation is irrelevant to at will employment.