I agree with this, and with what you said about the possibility to forfeit free speech if you are using it to violate another person's "Primary Right." There's a distortion somehow to the spirit of freedom that it can be used to take from someone else, who is supposed to be equal to you in freedom, their freedom, or diminish it at least - not all speech should be protected, and then we get into the value judgements and the slippery slope and all the other dark alleys of philosophy, but practically speaking it remains true.In some ways I don't believe freedom of speech even is a Right. I believe it's a privilege and a responsibility, and if you can't exercise restraint when addressing wrongs you feel, then you don't deserve it.
I am not sure I consider what Anonymous is doing to be "oppression" so much as "inconvenience" - there hasn't been a target I know of who wasn't fully capable of continuing their daily lives with only some embarrassment at having been disrupted slightly. I don't think the feelings they've engendered even in their 'victims' have come to a level to compare with those grieving a fallen soldier and loved one to the angry chants of homophobic head cases.