The funny thing about that, is that public school science education isn't politicized in that "both sides do it" sort of way. Where's the public school teacher who dedicated their life to the study and teaching of biology, only to disregard all of it and teach creationism at the expense of their students? Has it ever happened?
What we actually see, is that people who dedicate themselves to a scientific subject (almost overwhelmingly) accept the current best conclusions of that study and teach it accordingly. And even where those scientific understandings run into non-scientific beliefs, people tend to adapt their thoughts to complement one another. (e.g. "gaps which they fill up with God")
Abject politicization only really comes from the outsiders, who decide they don't like some part of our scientifically formulated understanding of the natural world and attempt to legislate it away.
So you rarely, if ever, see the problem as a teacher refusing to teach the subject they dedicated their lives to, or choosing to do an active disservice to the students that they pledged to serve.
And equating "tenure" with "preventing administrators from ever firing a teacher" is pretty ridiculous and politicized framing. It's more difficult to fire a teacher than a contract plumber, sure. But I don't think it's ever been shown to be more difficult to fire a teacher than a union plumber.
Which makes the gripe about "inability to fire incompetence" just a reframing of the old attack on unions and union contracts -- with little or nothing to do with tenure itself.