I'm not sure when's the last time you saw a courtroom, but asking for respect and decorum isn't exactly a new development. This merely formalizes and facilitates one aspect of it, which has been enshrined in human rights statutes and constitutional law. https://twitter.com/PardyBruce/status/1359167254504624136
Also, Jordan Peterson wasn't incorrect about human rights law protecting pronouns, he was incorrect about it being new or unprecedented. https://www.mcgilldaily.com/2017/09/no-pronouns-wont-send-you-to-jail/
Misgendering is know to be harmful. Trans people's full and equal access to the legal system is predicated on a minimum of respect being maintained. You can't call gay people 'faggot' in the courtroom, either. Is that "state-mandated identity politics"? https://www.healthline.com/health/transgender/misgendering
By your standards, all policies aiming at respect for marginalized groups could be cast as "not merely requiring civility but taking sides in a legal, political, and philosophical dispute." That's the thing with marginalization: it politicizes who you are.
So what you're saying is that by being enough of a jerk to a marginalized groups, you can make it so you don't need to respect them anymore. Only identities that aren't marginalized unequivocally end up deserving respect, because they're the only ones that aren't disputed...
It's also worth emphasizing that this isn't exactly a fight in which you still have a shot. Trans people have been protected against discrimination in Canada since the late 1990s. The 2010s bills merely made it more explicit.
And that Court decision you refer to involving a 17-year-old? If you'd read it, you'd know that it wasn't about the almost-adult's 'true gender' but purely about capacity to consent. So your point is completely off-base.
Moreover, the judge admonished the lawyer for misleading the Court by downplaying governing precedent and material facts about the mother's custodial rights.