Page is simply an exemplar of the role that perception plays in this.
There was a situation in a Starbucks somewhere in the UK fairly recently. An older female was buying coffee and wanted to pay with cash. The employee behind the counter said they don't take cash, only cards. The customer was a bit miffed, but by account of bystanders not really a problem, just complaining a bit about not being allowed to pay by cash while also fishing out their card.
Another employee came around the counter and told the customer to leave. the customer said something along the lines of "I wasn't talking to you, I was talking to her" referencing the cashier with whom they had been talking. The second employee then went on a bit of a tirade calling the customer a transphobe, clapping their hands directly in the customer's face, yelling at them to leave etc. It escalated beyond that and became a bit of a mess.
The salient point here is that the second employee was irate because the cashier identified as "nonbinary". But there's no good way for the customer to know that - the cashier looked female, thus the customer referred to them with female terms. The second employee wasn't offended because the customer was rude or antagonistic - the second employee was irate because the customer did not perceive the cashier's nonbinariness.
In personal interactions, courtesy is generally expected - but it's often not delivered. All of us deal with impolite, discourteous, downright uncivil people all the time. Heck, I've got a coworker who is a braggart and who is rude on a regular basis... but they get the job done and they aren't allowed to talk to customers.
When it comes to pronouns, and other sex-based terminology, however... there has to be some room for perception. I can't see anybody's internal feelings about themselves. If it's obvious that they're really trying, I'll either do what I can while they're present, or they get the same treatment you lot do: Everybody gets to be a "they".