I'd like to open another front on this discussion, and not get bogged down in the devil of the details.
The question I have isn't if creationism should be taught, by why would Christians want it done.
I believe that the fundmentalists want a forum for conversion, and they want it on the public dime. Clearly, they agree that science, as repulsive as they find it, has clout, because it works. People generally listen to scientists, they see the results, and they follow the logic and it makes sense.
Science has given humanity far more than religion ever has: the power to make thier own lives more fruitful, comfortable, productive and happier than any time in history. We can fly, go to the moon, cure diseases that ravaged civilizations and save lives that would have been lost before.
In short, science makes us more like Gods.
So obvioulsy, fundamentalists want a place on the platform. They want the legitimacy of science to rub off and make thier own hogwash seemingly as legitimate. No surprise, they did the same thing in the past with kings and princes, converting a ruler to convert the masses.
They want in on the action.
Having thier own tax-free churches isn't enough, because people are free to come or go as they wish. Church attendance is declining, and they can't fill the pews. People seem to have this idea that they can decide for themselves if the religion of thier fathers is worth practicing. They need something to make people believe. They need something compulsory. Something like compulsory public education.
So it comes as no surprise that they try to marginalize science into a "religion", a "belief system", to make it seem more like an opinion to people, so they might then claim a "rightful" place on the dais with science. It would be a coup equivalent to the legitamacy Constantine gave them, that somehow they could use the "magic" of science to make people believe. Especially those too young to deicide for themselves, and forced by government to be indoctrinated.
So I oppose the public schooling in creationism, even as example. They have thier churches, let them preach there. I'm not willing to give them time and space on the public dime, to encourage the further propagation of nonsense.