Unabogie
Philosopher
Actually, I don't how we should know that. The quote can be explained as not pissing off the base of the party he belongs to. His entry at wikipedia says he Roman Catholic, briefly went briefly to an LDS church, and makes no mention of creationism. A quick google doesn't turn up anything beyond this about him being connected with creationism.
So how should we know that's what he meant?
Only because we can combine two pieces of data.
1. There is no restriction on parents teaching their kids what they want and no movement to create those restrictions.
2. "Teach the controversy" is the slogan of the loony creationists in their desire to teach religion as science.
Since there's no reason to accept his statement as relating to data 1, then we can only assume data 2, unless you can suggest a third possibility. But since I've lived in America for longer than ten minutes, I'm very familiar with the slogans of the various factions and I can recognize their catch phrases when I hear them.