Now as to whether or not the author of the cited article makes their case or not, I'm with other folks who agree that if you're using gmail/docs/picassa/talk then you're probably already have this risk and Google+ neither adds or decreases that risk.
What it does point out, and the author doesn't explore, is that the Google+ infrastructure, binding these Google properties together, is what makes Google+ interesting. And it might be even more interesting if there was some sort of meta social operating system thing which would let you plug in the components you wanted (your email provider, your chat provider, etc).
I expect that if someone could pull that off they would get even more attention.
Facebook has a website with a serious credibility problem among mature users and growing fatigue amongst their core user base. A year from now you will not be taken seriously if you champion Facebook over Google+. And I say that as someone who has consistently derided their social offerings, although I will admit that Orkut was good for awhile.
Because gray areas and mixed bags can exist. g+ doesn't have to be perfect to do things right, and doing some things right doesn't fix other problem areas. There can simultaneously be upsides and downsides of the same thing.