These dudes are just another political pressure group. There are some on the list who haven't been in the CIA for more than a decade - in Stansfield Turner's case, for more than two decades.
They are damaging, however, in that they troll for information inside the Agency, and then make it public. How many things have you seen attributed to "former CIA" people? Those people are more than likely on this list.
Gee, I don't know,pop, if they're exposing classified information and undermining the CIC and DCI in the process, tipping off the enemy, they're more than just the Sierra Club.