Using "Google Plus" and "ghost town" in the same sentence is a red flag for not knowing what you're talking about. I get way more engagement on Google+ than I do on Facebook, and I've had a Facebook account for a long time.
Perhaps his Google+ experience is different then yours? I'm inclined to agree -- most people who I know have Google+ accounts, have added me to their circles (and vice-versa) but chose to keep all of their interaction on Facebook.
The groups of people you communicate with are different. Just like during the 90s, some groups used AIM, some MSN, some ICQ...
