In the passage I quoted above, I read it as suggesting that sex is special only because our culture has deemed it so, just as culture has deemed the word ‘fuck’ to be inappropriate, i.e. a ‘curse word’. My contention is that while the latter is a valid example of arbitrary cultural standards, the former is not.
Our reverence for the act of sex is not extrinsically conferred by culture, but something intrinsic to our neurobiology as social animals. It has been with us, H. sapiens, before the advent of culture itself.