I wonder if that is true. I am currently developing an application, which I haven't even added certificates to yet (or set a developer profile), but sending notifications to the Notification Center is no problem.
I also copied the application to another Mac and ran it there, also no problems there. I am not completely sure how to do it from a python script, but from within objC this wasn't a problem.
PS. Tweetbot for Mac also does it, without being in the Mac AppStore (still being in beta and all)