Fantasy, sci-fi and speculative fiction can do and say just whatever it pleases.
It has for some time been a bastion of independent and original thought. Look at some of the outrageous ideas put forwards by the likes of JG Ballard, Kurt Vonnegut and Philip K Dick. It's in this area of fiction where you find the outrages, not in the domain of cosy middle class Booker winning novels (much as some would like to think they are being unique - note that Martin Amis for one did a wholescale rip-off of Kurt Vonnegut in Time's Arrow).
I think the moral panic element has not a little to do with snobbery. It's perfectly OK for someone who appeals to the intelligentsia to diss religion (I could make a list as long as my arm here) and be morally outrageous (or even, just a wee bit challenging
). But as soon as someone does this in mass market fantasy which might appeal to the unwashed masses or in 'kiddies' books, then their wrists must be slapped. Reminds me of how at one time Bibles were only available in Latin, which of course restricted them to the priests, who then had control over what people believed.
But one element of fantasy that can't be ignored is the sheer lack of control of it all. Tolkien really and truly let himself go into it, that's how it comes across as genuine, and you can see the evidence as the language itself loses control into TT and RotK and. However Lewis did not lose control, Narnia is a bit 'constipated' as he got so bogged down with 'message' and all that. Now the weird thing about Pullman is he was trying to 'do a Lewis' but as the madness of the second and third books unfold, it's clear he too got carried away like Tolkien did - his creation took over his story. Same thing happens with Gormenghast as the story takes over and almost disintegrates. It happens with Earthsea too. And Harry Potter; for all those of you who have read book 7, notice how Rowling almost loses control of it all...