It is this behavior, instilled in us by female gender socialization, that destroys the lives of other women
By using "chosen" pronouns such as for tifs or tims, you are perpetuating the illusion of their rightness rather than being "polite." This behavior is harmful in any situation where a person engages in practices that are detrimental to them, but others not only remain silent but actively encourage them
It's better to be honest with your tif-friends and tim-fetishists than to give them the illusion that they should retreat into their distorted world
This is especially true for women. By referring to a woman with non-feminine pronouns, you are feeding her internal misogyny. Show her what it's like to be loved as a woman. Show her that being a woman is not shameful or limiting. Don't allow the patriarchy to use compulsive empathy against us, women.
This is not "personal life vs. political life," this is hypocrisy. If you are against fetishists who view being a woman as a costume and consider invading women's spaces a mandatory right, then you are against this. If you desire women's freedom, self-acceptance, and the eradication of misogyny and gender structures, you will not encourage the destruction of the identity of another woman you consider close to you. How can you claim to desire someone's happiness (as Rowling does) when you support their self-destruction and harm to others?