>Roger Dingledine does claim to "personally have met" 2/3rds of them
Hey said that he knew 2/3 in the beginning so 10 years+ ago and that it's no longer the case but he would like to increase the number of relay operator he or others of the Tor Project knows again. There are in person relay operator meetups at conferences (e.g Chaos Communication Congress) and I assume that he met most of the people at such occasions. I'm not sure why this should be terrifying.
>whitelist model (which is how Tor manages their high-risk exit nodes)
I'm not sure if this ever was the case but exit nodes aren't threatened specially than other relays and there is no whitelist model for them.