Tiny percentage of membership - and lots of them seem to be in places where child poverty is rife & the children/young people they teach will be impacted by a whole gamut of social issues they could be writing/signing open letters about.
And yes they absolutely can care about more than one thing. Problem is, we’re not seeing this kind of jumping up & down about other stuff.
Plus, of course, the horrific authoritarianism of it all. Again, lots of those teachers have just publicly identified themselves as teaching in places where large amounts of the population will be “transphobic” as a tenet of their various faiths. The stance they’re taking by signing that letter raises questions about their ability to work with those children [& their families].
Their brand of moral absolutism makes old-school Jesuits look like hippie philosophers. And certainly - whatever the truth of Aristotle’s oft-repeated saw - they’re not fit to be shaping young minds.