Can you cite someone who claims the earth created itself? A link or a reference to a text book? Sure, that does sound like it's nonsense, but it doesn't have anything to do with the matter at hand.
And which god's theory would you have taught? Suppose that Hinduism was the dominant religion in the US and that your kid's teachers were taching the Hindu version of creationism, which does accept that the earth is millions of years old. Would you be so sanguine about it?
Gesocentrism is another theory that has never been proved 100% wrong, and there are people who accept this as God's theory. Are you advocating yet another change in the science curriculum?
It is not a waste of time to show kids varying ideas, I agree, but there are ideas that are such nonsense that is is a waste of time to dwell on them for any lenght of time. Except when the nonsense idea has a relatively powerful lobby, then I agree that time should be spent in showing why the idea is nonsense and why the lobby is wrong.