That's a quote from "a former G+ product manager". His credibility is beside the point anyway... this was a hypothetical feature mentioned in the article that conveniently illustrated a potential privacy concern.
(To your prediction of how this feature might play out in reality I would say that you are probably right, but also that I don't give two shits about what my friends buy OR about what they publicly review.)
What we know for certain is that Google is aggressively pushing its users onto G+ and that is the real heart of the problem. It's a bait-and-switch. I have no intention of using Google as a social network and I have no guarantees that I will be able to opt out of current or future features. The writing is on the wall -- Google will be social. That upsets some people.
(To your prediction of how this feature might play out in reality I would say that you are probably right, but also that I don't give two shits about what my friends buy OR about what they publicly review.)
What we know for certain is that Google is aggressively pushing its users onto G+ and that is the real heart of the problem. It's a bait-and-switch. I have no intention of using Google as a social network and I have no guarantees that I will be able to opt out of current or future features. The writing is on the wall -- Google will be social. That upsets some people.