In 1985 in most places in the USA a public school teacher openly supporting gay rights in the classroom would have been risking their job and possibly their entire career.
The BBC had MI5 vet its employees for correct political opinions and associations into the 90s, and won't deny that they do it now.
https://www.thenational.scot/news/16176527.revealed-mi5-vett...
http://tonygarnett.info/mi5-and-secret-political-vetting-at-...
https://www.theguardian.com/media/2001/nov/14/bbc.research
The major difference is that captains of industry used to be able to almost completely dictate orthodoxy, and now in the age of the internet there are competing orthodoxies - some of which don't consider power and wealth synonymous with wisdom and genius. It also turns out that plenty of powerful people who control institutions don't care about being seen as philosopher-kings, and are happy to let their PR and HR departments deal with controversy. They will happily capitulate to all orthodoxies in order to protect the institution.
The problem is that labor rights have been overrun by freedom-of-contract at-will libertarians, so instead of people just hating you for things you've said and done, everyone also has to deal with apolitical sociopathic corporations that will excise you like a suspicious mole at the first whiff of controversy.
In an ideal world, our high schools would have taught the Constitution, the American Revolution, slavery, the abolition movement, the Civil War, Reconstruction, and Jim Crow, and on that basis taught the civil rights movement. They would have taught Homer, Virgil, Greek drama, Chaucer, Shakespeare, poetry and novels. They would have looked at modern explorations of identity such as Kafka and Dostoevesky. They would have taught the Bible and the basics of Christian theology and morality, not as Truth but as the mindset and background of most of those who have, to date, built up our culture. (Much as they might teach Marx as vital background for understanding historically important movements.)
They would also train students to think and reason for themselves, to recognize and reac to susceptibility to persuasion, and to detect and break down propaganda.
With these foundations, a student might then be able to intelligently study "gay rights" or gay identity in literature.
Those foundations are the first job of the schools. Let them do that before anything else.
There's a reason the conventionalists don't want real education for their children and zero involvement of society in their nuclear family: control. They then frame it as some libertarian ideal.
Until a public school teacher can say no to a student, and their parents, nobody will learn the foundations of complex thought in the classroom. That is by design.
In other words, for the same reason that a teacher should have "a position" on any other civil rights.