One reason to not commit on a visit is just to get a chance to sleep on it. I imagine things can be overwhelming when you're on campus and you might be prone to make a rash decision. If he wants to commit and still feels the same way a week later then he's probably making the right call.
If we can get Thurston, then let's do it. He can play both tackle spots, and is a consensus 4-star to all sites.