Isn't Readability an edge case? Yes, they offer a service, but they also offer content. By paying out the content owners, they are positioning themselves as publishers / content providers. They do offer other peoples content, not their own, which would make them different from a publisher.
Assuming it is an edge case, then Apple clearly pushed the edge further out to include more apps under the policy rather than interpreting the grey area in the developer's favor. Edge cases set precedent and the one set by Readability may raise reasonable concerns among developers.
But they don't act as a "gateway" to the content, so I don't see how they can be considered a publisher. They are effectively an XSLT script run through a remote server. You say to readability "here, make this webpage better", readability doesn't publish a list of formatted webpages.
(Although I appreciate they probably don't use XSLT and I don't mean to demean what they do).
