I think you're right here. This is a non-issue. Google's core value proposition to users is search. If that can be improved by gathering content from the + network, they will (and should do it).

If Google could have access to FB/Twitter content with consent, they would index and serve those results as well (it's fundamentally better for the user AND google).

This whole thing is getting blown way out of proportion because people like to see giants fight.