I think that it would be horrible if something like that were to happen. I understand that with the way the world is and the way it is becoming more and more, there are many same-sex relationships, marriages and parents; however, I don't think that anything like that belongs on a children's show.
It's so hard to be able to speak up for what you believe to be right. In today's world more and more, I feel like I can't say anything at all against homosexuality without being considered a horrible, judegemental, hatful human being. There is a difference between standing up for what you believe to be right and being hateful toward those who make choices you don't agree with. I am not for one second suggesting that those things should be kept out of children's shows in order to encourage hatefulness. I just think that we really do have to care what children are watching. Putting something like that in a kid's show makes it more normal and more acceptable.
I do think that it's important to encourage dialogue about topics like this with kids, but I don't think that as Christians we should be teaching them that it's right. Sesame Street is educational as well as entertaining, and that's important in a children's show. We just need to be aware of what it is kids are learning. It doesn't mean that we should ever teach them dislike or hatred for anyone else, only that there are things people are doing in this world that are not okay with God. (Obviously we ALL do things that are not okay with God.) As Christians, we should care what children are learning and they should learn God's Word and His will for their lives.
I understand though that no matter how hard any Christian parent tries, their children are going to come into contact with opposing viewpoints. I guess what I'm saying is that although we can't stop every negative or potentially harmful thing from happening, we just have to do our best. We certainly shouldn't be advocating for things like this, we are supposed to be separate from the world.