"Creationists aren't even on the radar screen for them, they wouldn't even consider us plausible at all."
And he's right. Creationist aren't going to get a voice on "Cosmos." Why should they? It's not a religious show. It's actually very secular. This is like asking why Atheist don't get thirty minutes on The Janet Mefferd Show. Because it's not an Atheist show. Nor is "Cosmos" a Christian show. However Christians can watch and agree with the show if they wish as well as Atheist can listen to Mefferd and agree with her. That doesn't mean that the show has to adhere to different believes. "Cosmos" doesn't have any beliefs what so ever. The show is based on scientific fact. Not an old book.
“Boy, but when you have so many scientists who simply do not accept Darwinian evolution it seems to me that that might be something to throw in there, you know, the old, ‘some scientists say this, others disagree and think this,’ but that’s not even allowed.” - Janet Mefferd
"Of the scientists and engineers in the United States, only about 5% are creationists, according to a 1991 Gallup poll (Robinson 1995, Witham 1997). However, this number includes those working in fields not related to life origins (such as computer scientists, mechanical engineers, etc.). Taking into account only those working in the relevant fields of earth and life sciences, there are about 480,000 scientists, but only about 700 believe in "creation-science" or consider it a valid theory (Robinson 1995). This means that less than 0.15 percent of relevant scientists believe in creationism. And that is just in the United States, which has more creationists than any other industrialized country. In other countries, the number of relevant scientists who accept creationism drops to less than one tenth of 1 percent." (Source) Still believe it's a large amount of scientists, Janet? I feel you will still demand for people to be scientifically illiterate. I'm positive you'll still push for unscientific beliefs to be taught in class rooms.