Nothing in the Facebook statement mentions the word dehumanize. You're simply inventing and adding a term in where none exists. It's talking about the view that

Nothing in the Facebook statement mentions the word dehumanize. You're simply inventing and adding a term in where none exists. It's talking about the view that transgenderism comes from a mental health disorder. Nothing in a belief, absent further context, that transgenderism is a mental health disorder is dehumanizing. Trying to link the two is so disingenuous that it's hard to take you seriously. Do you think when someone says anorexia or bulimia is a mental health disorder they have somehow dehumanized the person? Because in order to be logically consistent you would have to think labeling anything as a mental health disorder is dehumanizing.