The US constitution.
These guys are not employees of the school. They are paying customers.
That’s a good point. Christian florists and bakeries still have to serve sodomite customers, according to the injustice system, even if it goes against their beliefs to help celebrate sodomy.
So how is the Federal Government restricting their free speech?
Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances.