Perhaps this time they didn't blatantly violate Apple's rules by including major functionality that was completely hidden until enabled on the server, and not turning that on until after review. Apple wants to review the app users are going to see.
Previous discussion from back when that happened:
https://news.ycombinator.com/item?id=7194085That may be the case, but did any of the banned Bitcoin apps actually try to do IAP? How would Bitcoin IAP work, given the lack of inter-app communication in iOS?
It's probably more a case of IAP being the only sanctioned way to pay for digital services inside apps, with bitcoin transactions being a way to bypass the entire 30% cut that Apple takes for IAPs.