Bitcoin is a horrible choice for online payments unless you’re engaged in illegal activity or tax avoidance. Most people who acquire Bitcoins are hoarding them, because they’re speculating, because Bitcoin really works like a highly volatile stock (with some nice mathematical properties thrown in for geek cred).
Just the same, Apple wants a cut of every transaction, and Bitcoin apps won’t do it for them. Since they make no money on it and it might become a legal hassle, the path of least resistance is just to ban it. They can do things like this because they are a walled garden, which is why I don’t buy Apple toys.