It's not about guns per se, but about self defence. And guns are the best commonly available weapon (not talking about rockets or something here, I mean commonly available), so limiting their availability to average people IS limiting their capabilities for self-defence. Criminals will get them anyway.
And because homosexuality existed doesn't mean it's right. Unnatural means that it goes againts greater nature's plan for the species, not that it doesn't happen at all in nature. Lots of things happen in nature ( like autoimmune diseases), but it doesn't mean it's good when they happen.