“Should legitimate trade groups engage in rogue behavior, like denial of service attacks? Do the ends justify the means?”

Uh, isn’t this actually illegal? In which case I’d say legitimate trade groups (or any other group) shouldn’t be engaging in this behavior.

If you steal $5 from me, I can’t slash your tires and say “well, Evan stole $5 from me” as a defense – vandalism is still illegal.