I think the concern is though, that you might not realise what's being discussed in the classroom and what your vulnerable child is being exposed to.
Teaching gender ideology might not be on the curriculum, but there may be comments along the way when opportunity presents itself. For example, a child might refer to an unidentified person as male or female, and the teacher may comment that some people are neither as they're non-binary. Or they might say that we don't know what someone is until they tell us how they identify. There are better examples, but you get my drift.
You won't know about these comments until it's become entrenched in your child's mind and they start to repeat it at home. But by that point the damage has been done.
And the reason why I'd be particularly concerned is that there's a disproportionately high number of SEN children who identify as either NB or trans, so exposing them to this ideology at a young age is a bad idea.
I completely understand that withdrawing the child might seem excessive but I think the OP would have to extract cast-iron guarantees from the head that there won't be any comments around gender ideology in the classroom, or the introduction that some people aren't either sex etc. I'm not sure a head could provide that in good faith.
FWIW, I'd happily be friends with NB and trans folk in real life if they weren't twats about it so I'm not a crazed hater. But I think it's perhaps naive to suggest there's no risk at all here.