The problem with "first camp" thinking is that, most of the time, the emphasis on not stepping out of line limits your options while giving your opponent free reign -- as you cannot effectively force your opponent to do the same thing you are doing. This makes you ineffective.
The problem with "second camp" thinking is that, when you believe that the means justify the end, and you feel free to play fast and loose with the means, you will frequently end up with Pyrrhic victories, or just chaos (if you disregard consequences and still fail, the consequences are still coming).
I err closer to the second camp. I think what ultimately matters is effectiveness. However, I think it's important to keep two things in mind: 1)You still have the responsibility of weighing the potential consequences of your actions against the goals you are trying to achieve. 2)No matter what you choose, some people will think you went too far and others will think you didn't go far enough.
You, personally, clearly think that the protesters went too far. I happen to disagree, because I believe that what they are protesting against is more onerous and dire than the actions they themselves are undertaking. I don't think my judgment is binding and absolute, I simply agree with their judgment of the situation. I suspect part of why you disagree with it is because you don't think what they are protesting against is any big deal. I could be wrong in my assessment: there ARE people who would agree with you even if the protesters were there for whatever cause makes THEM hot under the collar, or at least if the situation were dire ENOUGH, they are just relatively rare. So my bet (based on how you phrased your objection to their behavior) would be that if you thought their situation was sufficiently dire, they would be justified in taking the actions they did. Hence, I am attributing to you the motive of thinking that whatever they are protesting is not a big deal.