It isn't about equality or fairness, it's about the core of education.
This isn't an issue of fairness or justice for transgenders, it's a issue of classroom control. By allowing students to force a teacher to use a preferred pronoun under penalty of disciplinary action, you are making teachers dance through a minefield of potentially ever changing preferred pronouns. Accidently say the wrong one and it will blow up on you. Teaching needs to focus on the education of core elements: language, reading, art, math and sciences, not on an indeterminant game of "Guess the pronoun".
If you feel you need to have a policy, make it suggested one where the teacher uses a student's preferred first name or their last name when addressing them personally or talking about them in the third person. Again, make it suggested that the teachers do this, not under penalty of disciplinary action.
Thank you for allowing us the opportunity to address this issue.