The whole point about sex and relationship education in schools is that it is planned, proportionate and progressive, so it should be age- suitable.This is a good thing. I would want kids to have some understanding of the biological differences between males and females, as well as things like puberty,preferably in advance of the onset of puberty itself. School is, after all, designed to educate children and provide them with the knowledge of how to cope with adult life. no?
Being embarrassed by questions from a 9 year old just sounds a bit weak, IMO.
If it was education involving the screening of "Debbie Does Dallas", or practical demonstrations using condoms and cucumbers or similar I could perhaps understand the objection - but that's not my understanding of what is actually covered for kids at primary school.
It is also my understanding that kids are given consent forms that the parents have to sign, so they surely should not have been taken totally by surprise...