For better or for worse, posting in a specific forum does not limit the audience- many people don't even notice when things are posted in a specific forum. On the bright side, although you did perhaps break GC etiquette by calling out a specific organization, you didn't post the same message in 5 different forums telling them all that you want to join them and only them
Yes, it's been done... all too often. Sounds like you just didn't quite realize how what you had to say would come off.
You likely will not be able to delete the thread (not really how it works around here), but if you stick around you may want to keep things less org-specific. And if you do disappear, I for one would like to hear how things go if you do decide to go through recruitment. Take a look at the "Recruitment Stories" forum and you can check out many different types of experiences & endings, as well as some great advice.