I agree to some extent that it makes sense to consider DDOS as a form of protest*.  I'm less sure about whether I agree with their reasoning though.
Corporate greed is a hard thing to solve, and I don't quite subscribe to the idea that, "if customers don't like it, they'll leave" - I don't think DDOS attacks necessarily change the culture.

* Unfortunately these days, DDOS attacks don't exactly need to be initiated by multiple people.  Attacks via botnets or reflection+amplification type attacks can be started by just one person, and it's hard to argue that as a form of protest.  If many people actually launch a DOS attack, then it makes sense that they're protesting, but then, DOS attacks like these without any form of identity masking is dangerous for the ones doing the attack...