This became more of an issue for me recently because one of my best and oldest friends, who as it happens is a TERF, has become seriously estranged from her daughter, who wants to go by "they." For my part I don't have a problem with this, but it's way more difficult for me to to remember to refer to my friend's daughter, who I knew as a bump, as "they" than someone I met recently.
My friend, who from here on out I'll refer to as "R," believes that her daughter's ("L's") problems grow out of the medications she is taking, one in particular.
This is plausible because L has broken it off with three old friends, including my daughter who she has known from infancy. In my daughter’s case the beef is that L doesn't like my daughter’s girlfriend and basically demanded that she choose, and my daughter chose to remain loyal to her partner (and fiancé), as I would expect and 100% support. I consoled her by pointing out that it does occasionally happen that people we thought we knew turn out to be a-holes.
Talklng to R the other day I suggested that she simply cave on the whole pronoun issue as a way to begin to repair her relationship with her daughter. It's weird because L still gets along with her stepfather, who also has no time for flexible pronouns. But my point was that R, who has always resisted using "they" with her daughter, concede the issue as a way in.
R is quite adamant about such things. According to R, trans women (who she refers to as "guys in dresses") worm their way into women's spaces then, having been socialized as men, begin dominating conversation, etc. Not being part of women's spaces I know nothing about this.
L certainly shares her mom's intransigent nature, as I pointed out.
Sorry if I have rambled a bit, but life is complex.