I think there's a much more reasonable explanation.

We know that TSOs are specifically enjoined not to discuss SSI with anyone outside the agency, and can be sanctioned for doing so. Even though the information in this document is now completely public, it is still technically SSI until The Powers That Be declare otherwise. Consequently, there's probably no way for our TSA friends to actively participate in this discussion without violating the rules imposed upon them.

(This is hardly unique to TSA. When Valarie Plame Wilson wrote her book about her experiences as a covert CIA officer, she wasn't allowed to discuss certain topics, even though the information on those topics was in the public domain. As I understand it, her book has numerous places where this "secret" information is blacked out. To know what's there, all you have to do is go to the afterword in the book, written by her mother, where she fills in all of the details ... because Mom wasn't bound by any oaths of secrecy.)

Anyways ... I think our TSA friends are out there reading this, but are silent because they really have no other choice.