I think we need to be cear about what is possible and what is probable.
The possibility that things could go badly wrong if someone publishes identifying information on GN is one thing. The probability of that happening is much much lower.
To begin with, someone might admit to a birthday and six months later say vaguely where they live. But scamming is an industry, and scammers do not have time or inclination to comb websites like GN carefully extracting tiny bits of information to build up files.
That will only happen if the police, security services or similar already have information on you and are investigating you in detail. In which case, they may get your GN details by other means. The other real threat is close friends or family, where they can find out your user name in your home because they see your computer/phone and possibly check it. That. as I discovered, led to my original cover being blown.
Scammers are an industry and they want data in industrial quantities, so they will go for banks, and financial institutions, govrnment organisations etc, where they can obtain a lot of security data on thousands or millions of us in one sweep.
I have made one very good friend through GN, I responded to someone I had deduced lived near me, although I got the town wrong, at a time of her need. It turned out she lived even closer to me than I imagined. She could, of course not replied to my PM or rebuffed me, so I still would not know to within 15 miles where she lived.
I have also enjoyed meeting people at the Oxford meet-ups. If any one was watching one of us from another table, it will have been because of some other aspect of that person's history that made them a person of interest, certainly not their memebership of GN.
We do really need to see things in perspective.