The premise is: sex is binary, gender is fluid. Just like our brains are fluid in their capacity to generate thought and action. Seems fairly straightforward, unless you believe that the human mind is a prison, and that consciousness, thought and choice are an illusion. If that's the case then there is little point to humanity itself. I prefer to believe that if a person's choices aren't hurting others, then what business is it of mine. So in this scenario how does this hurt you?
I believe we have freedom to choose many things, including our gender based on our underlying genetic structure and the environmental factors that make us who we are. In some cases choice maybe almost compulsory, due to some deep fundamental incroguity such a conflict between sex and gender. In that case technology enables a person to make the choice to modify their sex and hopefully eliminate that deep incroguity within the core of their consciousness.
In these special cases we can even say that there is little choice I'm the matter, it's akin to pulling out a thorn from their side. Sure they could choose to live in pain and leave it alone. But we've advanced technically and are able to remove that thorn for some folks. It's not end of days and the plain ol P and V still reigns supreme, progress. Who cares, I'm more concerned about the economy and taxes