How about a note, edited into the post (letting her own text stay), something like:
Hi and welcome. It's nice to have you here. For future reference, this thread is for (insert slug summary here). If you'd been here a while, we'd have deleted your post, but we didn't want to scare you off. In fact, we've had this big, long, goofy, circular conversation (if circles can be long) about how to let you know all this, without making you feel like you were being run out of town. Which you're not. Because that's what we do ('that's what we do' refers to us having goofy, circular conversations, not running you out of town - because we don't do that).
So again, hi and welcome. Take your shoes off. Make yourself at home. Acquaint yourself with our FAQ and come on in the pool. The water's fine.
...
And yeah, this belongs in bureau, but the rest of y'all are lost, so I'm responding here. Here's why I think we should say something. We should say something, because we delete regular posters' misposted-in-press-posts, all the time. People have just complained about regulars posting celeb death mentions in press. I don't get the double standard, and I do believe although we want to welcome newbies, we want to welcome them to our culture, a part of which, is respecting the Press thread purpose.