People don't get pressure to 'come out' as straight, so I don't think that there is any obligation for gay people to declare their sexuality.
In the 80s (or was it the 90s?) there was a trend for celebrities to be 'outed' using the logic that staying 'in the closet' was delaying normalisation of homosexuality. That trend stopped ages ago - maybe when Jason Donovan sued, saying that he had a right to privacy. I agree that people have this right, and should not feel that their private lives need to be made public.
As for PS and the timing of his announcement, well, time will tell. It does seem a bit odd that he's decided to talk about it after all this time, but that is his choice, and if there is scandal behind it I doubt that any pre-empting of it will make any difference. It's just not a big deal any more, and I don't think that people will be sidetracked into excusing any impropriety if that is what has happened. If it hasn't, then it will all die a death and normal business will be resumed when the next talking point comes along.