There's more to this than meets the eye.
Are you aware, the assistant head at the centre of this row, wrote (and stands to benefit financially from) the materials?
Is he really interested in promoting tolerance and inclusion in his school, or in using his school to promote his program?
That may all be the case, but the argument made by the parents (or possible just the most vocal protesters) doesn't seem to have been one about a conflict of interests or 'more sensitive ways to go about this'.
"Fundamentally the issue we have with No Outsiders is that it is changing our children's moral position on family values on sexuality and we are a traditional community.
Morally we do not accept homosexuality as a valid sexual relationship to have. It's not about being homophobic... that's like saying, if you don't believe in Islam, you're Islamophobic."
Looks like a pretty clear cut (and ridiculously badly argued) case of bigotry to me rather than anything more nuanced.
I also don't think it's massively helpful to support this position just because posters feel the materials may contain (do they?) inappropriate messages about transgender issues. If the T part of the materials is problematic, make your own argument, preferably based on science and reason, rather than share a platform with religious fundamentalists (wether Muslim or Christian).