Someone recently said that Dawkins has gone on record saying that he won't debate creationists because he doesn't wnat to give them an air of respectability. I don't know if Dawkins actually said that; but I will comment on the described attitude. It reminds me of advise purportedly given to candidates seeking office. If you are behind in the polls, seek a debate. If you are ahead in the polls shun any debate you can.
Creationists currently have no argument. They simply say something on the order of "it's too hard to understand how we got here, therefore god must have done it." A debate against that would "lend respectability" only in the eyes of someone who is not actually looking at the arguments. Avoiding a debate on that motivation is only seeking to keep people believing your position uncritically. I expect that if most people believed creationism, creationists would avoid debates for the same reason.
Now, this isn't to say that there aren't good reasons not to want to debate. Perhaps he is simply not interested in whether uncritical minds agree with him or not. Consider, it is not important to me if people believe the world to be flat. I make an exception for rockets scientists and sattelite engineers. People in fields like that need to know the world is round. But they need to know based on the evidence, not because that is what they are told. It doesn't matter if a surgeon believes the world to be flat. It's not going to change how he does his job.
I am convinced that some things are taught in elementary school only because religions preached the reverse. That the earth goes around the sun is meaningless to a young child. There seems no point in insisting that they believe that. And they will only be believing that on the authority of the instructor. For people for whom the fact is important, the evidence will be part of their eventual studies. Furthermore, someone committed to either position based on what they were instructed when he was young would make a very poor scientist. So, it shouldn't matter if the church is teaching geocentrism. Any worthwhile scientist should be able to revise the belief based on the data.