There is a divide between children seeing all kinds of things and knowing they are there and being taught to behave respectfully to all, and teaching them around the nature or ethics of those things specifically.
If we accept the principle that state schools can and should do the latter, we all need to accept that it is perfectly possible that at some point, if the public or certain sectors take a different view than we ourselves do, we will simply have to accept that being taught to our kids. Or remove them to some form of private education.
It's also arguable that all education will involve some of that kind of teaching, and the question is where to draw the line. But that doesn't make it a whole lot easier to decide where the state's views takes precedent over parent's views.