"When it comes to gender identity it is a real and valid concern for a number of students."
Only after they learn that gender identity is even a thing that some people pretend exists by having in forced into their lives by the schools 'curriculum'.
"For us, anything that prevents students feeling happy, from feeling confident in themselves and from feeling accepted by their peers is something we feel the curriculum should address."
Except grading scales, homework, detention and politically correct standards of behavior. Just as long as they conform to what we think they should conform to, we want them to feel comfortable and happy!
I would take my son to see a professional too, a professional therapist.