“This has been just an enormous distraction,” Dr. Stein said in an interview from the district’s foothill-framed headquarters. “It has added a lot of stress to the system and to the kids who are being targeted here.”

What the district cast as a practical decision is viewed as a rare counterstrike from public schools, universities and hospitals in support of a transgender rights movement that has been on its heels under President Trump after a decade of hard-fought successes in school board rooms and courts.