> If anyone can pick their gender, what makes someone masculine and what feminine?
I don't think this really follows. There are still traditionally masculine and feminine traits, this is unchanged by people self-identifying as a gender other than the one they were born with.
I'm not against transgender, I'm just arguing on technical grounds. I don't see value in using gender-specific words if people can pick their gender, but I do see value in using them purely to distinguish between people by what is between their legs.