A good education is paramount to success in life, and key to a good education is a safe, supportive environment for all students to learn in.
That safe, supportive environment must be gender affirming. Not only will it drastically improve the lives of trans or questioning students, it will improve the lives of cis students as well. So much of the stress of middle and high school revolves around trying to conform to the arbitrary standards of masculine or feminine imposed by society. Breaking down those barriers, showing male kids it's okay to like "girly" things, or female kids it's okay to enjoy "masculine" activities, as well as just more activities that put male and female students into the same arena where they can interact in non-gender segregated ways will help students grow up without many of the toxic stereotypes that infest our thinking.
Support for Trans kids is support for all kids. Making schools safer for trans students makes schools safer for all students. I fully support this proposal, and note that those in opposition aren't actually concerned for students. They're simply uncomfortable with the idea, or just straight up bigots.