I'm fairly sure that the argument presented is illogical. although I cant be bothered doing a truth table. However, the argument is also wrong in it's premises; the argument works on a idea of relative scarcity,or lack there of. A gay can marry just as any other person can, so this is fair right, they aren't denied of anything given to others right? Wrong, there is a hidden premise in the argument that it does not acknowledge it'self: that 'straight' marriage is accentually a means to happiness. Therefore, gays do not achieve the same satisfaction as heterosexuals from this scenario and are therefore being denied something the majority of the community has access to.
my 2 cents.
my 2 cents.