I think that is the most straightforward interpretation, setting aside the special AA/US benefit discussed in this thread:
http://www.flyertalk.com/forum/ameri...22-2014-a.html
SPECULATION: It might be that American Express will require selecting AA or US as the carrier for the primary benefit to be eligible for the additional benefit.
I don't think they mentioned that in the email they sent out. That would be a pretty big about face.