Not really
If my daughter had been told anything about sex or sexual relationships when she was six, I would have had serious words with her school. I've looked at the book in question and, even though it's pretty subtle, it still shows people in bed together.
She's eleven now, and I would be perfectly happy for her to be told about all aspects (with care) of human relationships, more so when she gets older and able to understand better.
I've just blocked an app from her phone (Tiktok) as it's being used for gathering data about children by the Chinese owners, and being used in India to spread porn - Am I a dodgy cunt for protecting my kid from that?
My objection is the age, not the content.
You might very well think teaching that stuff to little kids is fine, but I do not and, further, would consider anyone doing so, or supporting it, to be dodgy cunts.
I fully expect someone to tell me kids see their mums and dads in bed so it's fine, but a gay or whatever couple's kids see their mums/dads in bed, so that's already looked after for the appropriate percentage of the population. If such families have kids in any given school and the subject comes up for any reason, especially bullying, then a carefully measured bit of social inclusiveness instruction is perfectly reasonable.
Then we come to the rights of given groups, and who should be oppressed in favour of whom. I don't think it's right to oppress anyone, Muslims, Jews, LGBT, parents, whoever, so a very careful line has to be considered. In a school with no such families, why bother until the kids are able to understand basic relationships?
Anyway, in response to your accusation I'm a "dodgy cunt", I believe I'm a good dad for protecting her from learning about the wrong things too young, but teaching her all people, regardless of race, skin colour, sexual preferences, or anything else, are perfectly normal and acceptable and, most importantly, regardless of differences, we're all the same.