I am not for boycots in general (unless it's a boycott of Smith&Wesson). Also, the case is murky. By going after fansubbers Media Factory violates the honor code. If they made the anime, upon the discovery of it, I would consider myself not bound by it either, that much is clear. However, what happens to my responsibilites to J.C. STAFF?
The Solomon solution here follows. Even though I saw and enjoyed a few episodes of ZNT by accident, I'm not obliged to buy DVDs. I am decrementing the ZNT's priority in my queue by a few points. This means that, if I buy anything, it's going to be a deeply discounted DVD.