It isn't showing up in the tag list for me at all. This is the tag list I get for that section:

subject:pwp subject:pwp/slice.of.life subject:queer.issues subject:realisations subject:relationships subject:rescue.attempts subject:resigning.from.mjn subject:romance subject:sci-fi.elements subject:secrets

A direct link finds it, but I think perhaps there's some sort of filter blocking it from the list for people who are not logged in Pinboard users so it can't verify age and the tag has the word sex in it?

Direct link below.

http://pinboard.in/u:cabinpressure-fic/t:subject%253Arough.sex/