Matt Horne must be some kind of simpleton if he thinks life is as black and white as that. He has no idea what is involved in some people's reasons for staying in the closet.
I agree that if it's purely a case of worrying they won't get offered the roles they want in films or if women will go off them, than yes that seems pretty poor and does nothing for gay people in the industry, only serving to keep perpetuating the inequality. But, I would say that is rarely just the case. Most often, people are in the closet to their families too, which must cause emotional distress and anguish. Perhaps their families won't accept it or they have an issue with accepting their sexualities themselves? Either way, it is no-one else's place to pass judgement on others. Just because someone happens to be in the public eye, it does not mean that every detail of the personal life should be made public property.