Many Ts do this. It's not paranoia, it's just the awareness that everyone with a profile is opening up personal info to anyone who is curious. For some professionals having their private info seen by clients can lead to more awkward situations than it would to others. I've heard about many people on PC and elsewhere who found their Ts online and ended up wishing they hadn't. I known some teachers and lawyers who do the exact same thing so it's not limited to therapists. They're not narcissistic at all. They might be a more private than the average person (especially people who grew up on social media), but they're mostly just aware of the downsides and would rather avoid any potential problems. Social media isn't as much a part of everyday life to a lot of people 40 and older so staying off it doesn't have the implications that it would to a person on their 20s or 30s.