There is nothing wrong with him wanting to be a woman if he is a grown adult who isn't around children for a living or in general. He has every right to live in delusion, but don't force me to acknowledge that delusion and most importantly don't force children into that delusion until they can make up their minds as adults to acknowledge or participate.
I don't have any problems with grown adults doing something that does not effect other people. When they continue to push for everyone to engage their fantasies, that's where I draw the line. They have already made it illegal in some states (California) and Canada and the UK to misgender someone. You could literally be fined or put in prison for calling a man a man when they identify themselves as a woman. THAT I have a problem with.