What people do in their own bedroom is their business. There is no good reason that a state ban on sodomy is justified. It two or more people are of the age of consent, I really don't see any reason to ban them from doing what they want in the bedroom.
Any form of consensual sex or sexual acts between two adults of legal age should have no regulation by any government entity. So long as the participants are committing no crimes (such as rape, molestation, forceful sodomy, pedophilia, and so on) then there is little, if any reason, to say that sodomy bans are justified. As with most debates, anyone of legal age doing something they feel is okay for themselves and in no way harms anyone (without consent especially), shouldn't be governed.