I suspect spilk is referring to concerns Apple will probably have had internally about rival payment platforms using the iPhone NFC hardware to process payments

I suspect spilk is referring to concerns Apple will probably have had internally about rival payment platforms using the iPhone NFC hardware to process payments instead of Apple Pay. I'd be extremely surprised if debates about this didn't come up when they were deciding how to build the public API for the feature, and is probably a huge factor in the API being read only and not supporting card emulation, for now.