What's the point of PM ing you? You've already made up your mind. Presumably you've never had your time wasted by these people.
As regards sexual orientation: surely letting people know what you're looking for isn't too much to ask, is it? If the guy is straight, bi or whatever that's not a problem but he could let people know beforehand what he is looking for. It will save a lot of people a lot of time as I'm sure he receives a large number of replies.
If you let him continue to post he WILL waste a lot of people's time with his vague adverts which appear once or twice a week.
If bobo disagrees why doesn't he post a response himself? Better still why doesn't he place a useful advert and stop messing people around?