In a text I've come up against this and I can't get my head around it. Could anyone please give me some idea?
I was google-searching and I just found this too, "The public irrelevance of modern poetry."
I'm at a bloody loss!
Modern poetry is not relevant to the public.
As far as the public irrelevance of sexuality, I imagine it means that no one (apart from a few religious nutters) gets het up about someone else's sexuality anymore. Doesn't matter if you're hetro, bi, gay, monogamous, polygamous, costumed, celebate, or saving yourself for aliens.
Public irrelevance can also be a matter of prudence, hence 'discreet' as in 'lying low'. It could also mean a lack of consequence, such as a 2011 upgrade for a Betamax video player. :)