I imagine it's for two reasons. One, nothing will be accomplished. When the dust settles, the supporters of Creationism will still support creationism and the supporters of evolution will still support evolution. All is does is give creationism a thin covering of science. And two, come on. It's Bill Nye, a kids show host. Do you want people to think he's speaking for you?
Yeah, OK, like evolution strictly follows the scientific method - anything historically-based is not a hard science. It does not follow the scientific method. It is neither observable nor repeatable. And it is not falsifiable so it really doesn’t matter who is included in the debate, just a bunch of hot air [no, not referring to global warming - another hoax of our times].
Spoken like a true product of public school education.
Ken Ham has also done a lot more research than Nye on this topic. He’ll mop the floor with him.