Since they demonstrate the tactical capacity to put a bunch of people in a place, at a time, without law enforcement getting a sniff of it beforehand.
Don't think of it as terrorism per se: think of it as a people-organizing toolset, and it ought to terrify any police state who's paying attention. To the extent the US behaves like a police state, this is a threat.
Take a look at Improv Everywhere's Cell Phone Symphony. Heck, much of what IE does is militarily relevant. It says, "We're a bunch of peaceful clowns. But if we'd wanted to get you, you'd have been got". It says "Your security theater is irrelevant".
You're conflating a 'customer-support' interaction with the criticism role. I won't dispute that lots of linuxy and open-sourcey communities are not safe for tenderfeet: you're absolutely right.
But it's a different topic.
From mailing lists and public bug trackers, my sense is that there are plenty of critics, and they are frequently able to find the right place to criticize.
I think that the extent of criticism within the system reduces the need for lobbying in the press to get your pet peeve addressed.
I judge a religion as being good or bad based on whether its adherents become better people as a result of practicing it. - Joe Mullally, computer salesman