The scare part refers to warning dialogs that iOS would pop up if you used a link to an external web browser to collect payments. It would warn you that Apple wasn't running the payments and use scary language warning you about potential fraud, etc. to try to scare people away. They would also demand a 27% fee from developers for collecting money on the web outside apps if users were paying from following that link.
I've been following this project for a while now, and it's incredibly ambitious. It will take a while to reach its full potential but Jarred is doing an extraordinary amount of very good work on it, and I think there is a very good chance this will turn out to be a pretty big deal.