There is such a thing as opportunity costs and political capital. You only have so much of each. Spending some to defend Johnny come lately from your own supporters needs to be worth the cost. This keeps getting glossed over. Gay marriage in particular and gayness in general is a really big deal to a chunk of the right. It would be like someone saying that they want to join the Conservative party, but you have to accept that all the current gun control was/is totally legit and that they are going to vote for more if it comes up. They are totally on your side though, they just want you to understand that the fight for your guns is over.Pander is diffrent.
We arnt saying the LGB have to be pondered to. Just treated equally
Also what else can you call it but pandering? There is no heterosexual lobby. Otherwise normal crimes get a special upgrade and attention when done to LGBT people. They have special laws and social protection. They have preferred hiring quotas and firing one risks additional special lawsuits.