"Linking to a site which meets any of the following criteria in a post is prohibited:
Advertises, suggests or even hints that minors may be discussed or portrayed on, or contacted through, the site.
Contains Escort Reviews (Ex.: ECCIE, Erotic Monkey);
Has Pop-Ups (Ex.: Porn and cam sites);
Is likely to contain malware;
Requires login (registration) for viewing the contents of the site (Ex.: Facebook);
Is absolutely irrelevant to the subject;
Belongs to a private business or which offers specialty services (Ex.: Ashley Madison)
[sic.] Positng mean or rude comments is prohibited."
I recall the post and that the thread was active a while -- I just don't recall if it was one of those threads that took a bad turn into flames or something.
Or could just have been something where some file corruption trashed the posts but not the index record you see in your view and were not recoverable so that was the best reason they could offer.
But like many things with TER administration we often never hear the why.