So, I see some nuance here.
People don't change, *unless they decide to.*
What can you change? Extrinsic things, like ideas, ways of thinking, even core beliefs.
What can't you change? Intrinsic things, like sexuality, gender, genetics.
This dichotomy between intrinsic and extrinsic is where I mostly see the lines for protections. All intrinsic things should be protected from discrimination. I also see use cases for some extrinsic things, like religion (or lack thereof).