There's also the push from some members to get pedophilia included under the umbrella of LGBT, with varying levels of sincerity. Not to say that this is happening or isn't nor my opinion on the matter, but that's how the perception that widespread acceptance of homosexuality has led to a slippery slope has arisen and gotten a strong foothold to many people.
Either way, people are free to change their political leanings. Since the two party system seems to exist strictly to contradict each other, one side is going to look appealing when the other goes nuts. It just so happens to have flip-flopped over the course of a decade.