So - yes.
Sure, you're going to add more qualifiers now, but I'm giving a counterpoint to your original claim.
As the masses (and I mean MASSES) of people buy into the social media explosion going on all over the planet, these "low-profile" individuals will A) become rarer, and B) start to look suspicious. Whether the sub-population of computer engineers see it for "what it is" or not; the general population apparently doesn't.
Example: I have a friend who, begrudgingly, created a Facebook account and used it rarely. Several months in, he started getting "friend" requests from (presumably) middle-eastern men, often shown with photos of AK-47s. If this is not a clear demonstration of a IS NULL business rule to figure out who might be anti-social, I don't know what it.
I stand by my prediction as well: Over time, a lack of an online presence (in a world where online presence is virtually required to live modern daily life) will be deemed "anti-social".
The lure (both ease and historical/digital facts) provided by scanning social media history will only grow in popularity.