Developers submit binaries to Apple for review and posting. Apple uses binary analysis tools to ensure that apps aren't using private frameworks. They probably also look for signatures that indicate the use of Flash frameworks or other "banned" technologies.
When a developer submits an app to Apple, they state they have the rights to distribute the application. Apple could care less what the licensing is for the source code.
The primary reasons for Apple to reject an application (according to Steve Jobs) are:
1. Doesn't function or do what it says it does
2. Uses private APIs
The first reason is also why many applications get rejected for what people would assume are source-code violations. For example, Apple won't allow interpreters in apps. They aren't scanning through source code, they're looking at developer-provided descriptions. If a developer says you download scripts to their app, Apple will reject it on the assumption you're interpreting the scripts.
I have no opinion on whether Apple can be considered a distributor or not. But you need to base your decision on the facts.