RAFOnauts have a little more sophistication, or so I thought.

Did you read "Backup"? That's one of those things in the Dresden-verse where there might be good reasons not to ever talk about bad stuff.

There's more to it than the whole security issue. Talking about it might actually be a good way to become infected. I mean, if security was the only concern, then Harry should not have been asking "Is it okay to say 'adversary'?" when he was alone with Mother Summer. I mean, this is a Queen and a Knight of two Faerie courts, alone in a part of Faerie under her influence (as they were traveling really fast), and they are still avoiding the word? It can't be as simple as a security issue. Lea & Mab have been rather frank about the fact of her infection since back in Dead Beat, but careful not to say the name or discuss the nature. I think it's something more than letting Nemesis know you're onto it - I mean, Maeve was infected, and she was a witness to Harry being told, and the Outsiders must know he was thwarting their plot, so his awareness is hardly a secret. But they still keep it secret, not because they fear the attacks of its minions (I think if I'm doing the thinking for Nemesis, I have to assume people like the Faerie Queens would know anyway).

Maybe they just explained it badly, because aside from the logical issue you mention, there is the point that the excuse is not even consistent with their behavior anyway.

Butcher seems to be fairly receptive to issues like that, because I can recall occasionally running across some odd thing or other Harry says that doesn't seem to belong in the book, but which makes sense as Butcher lampshading a previous mistake. The one example that springs to mind is Harry taunting Peabody in his office in Turn Coat about the German error in the title of his book about the Erlking. Kind of an odd thing for Harry to snark on, unless you figure that's Butcher's answer to all the Germanophones who gave him crap about it. I'm betting a future book will have some clarification about the First Rule of Fighting Nemesis.