First, it wouldn't surprise me if Apple wasn't involved in this from inception on the grounds that rival companies have been copying Apple within weeks of a new product release if not before. Ergo, Foxconn in China must be the leakiest place on the planet. China is also one of the worst places for intellectual property rights. So, by manufacturing in the U.S., Apple might be able to maintain control over the IP. Maybe.
Second, with regards to people laughing when Trump initially said that Apple would be making product in country, given his deep business experience, he likely knew this was going to happen early on. Good business people know things before everyone else does.