Quoting Legendary Amanda:" I voted not to ban, simply because it's too hard to put in place. You can't really determine that they've ... [snip!] ... a bg secrets post about it, if someone were to bring it up, who's to say I (or someone else in the ptot) didn't tell them?"
when the member is clearly connected to their post in that situation or elsewhere publicly it's irrelevant HOW you came by the information, rather that you're pinning their post to them.
if you make a statement that could be a clue to who it is, that's not the same. for example: "but what about how your daughter feels about all of this?" ... it's clear you know more than others (or at least think you do), but it doesn't remotely identify the poster. anonymity is preserved.
if you - on the other hand, were to say, "but you're gay, we all know it. you even posted it in BG secrets, which we thought was ridiculous considering how un-secret this fact it", you should be banned.
if you go into their BG secrets topic and attempt to identify them in a way that is clearly malicious -- and even if you're wrong, you would be banned for being an smurf of the first degree.
certain behaviors aren't tolerable, this is one of 'em.