As much as I don't like it, I have to agree with your logic, it is sabotage. That having been said, politically correct protests and pickets are not exactly possible to do using the tubes. If you chose to picket a brick and mortar store, you would be able to physically interact with people walking in and out, you could be holding signs that they might inadvertently read in passing and maybe change their mind about doing business in the store. You could be chanting some clever slogan about the evilness and corruption that people would be forced to hear, and so on. How would you accomplish this on the internet?
Yes you could start something like www.paypalsucks.com ... That site has been around a few years, and has it made a difference?
If I was said customer, how would you get your message to me about the evil of paypal if I type paypal.com into the URL bar and go directly to their site?
Now, if there was a way to set up a legal virtual picket, I would be all for it. Something like, briefly redirecting users to a page with protest signs or whatnot. But then guess what, every single site would get "picketed" by somone or other.