I am one of those who is quite happy that the FlarmNet database was shut down. I did register (years ago) so that I can meet buddies in the air or know on which frequency the guy opposite me in the thermal would be. I did NOT register to be tracked by anybody sitting in front of a screen.
So when I learned about OGN, I deleted my entry into FlarmNet - pitty, though. If OGN would have provided an opt-in, everything would have been fine - but they didn't. They even didn't provide a opt-out (other than what I did, or switching to stealth and deal with reduced warning modes). Noboday actual knows who "they" are. If only one of them disrespects the stealth flag, you can't avoid being tracked.

Now Flarm has decided to put that on a reliable track, and that's fine with me.