Low 6's here, and only because I waited 2 years before actually signing up--otherwise I'd be what, only 4 digits?
I have many friends that have deleted their FB profiles for various reasons. They are still social, active participants in the *real world*, which is what matters.
Seems that depending on your personality type, the relation between your FB activity and in-real-life activity is either directly proportional (you're already a social creature), or inversely proportional (and with a high coefficient)--because even if you're introverted you still seek social interaction--just preferrably via distance communication.
Regardless, attempting to infer any meaningful information from someone's online activity or lack thereof seems a stretch (unless they explicitly blog all of their activities and opinions--and assuming they are *truthful* about all of it).