Why don't other distributors contribute? His gofundme says this could set a precedent for them to be sued. Seems worth their time and money to be sure this goes away now.
If he were to settle, there would be no precedent set. And even if he went to trial and lost, other District Courts would not be bound by the determination in the Gwyther case. This would only be considered as "persuasive precedent", which courts ignore all the time (see, e.g., every circuit split ever).
To be clear, I agree completely that they should band together to nip this in the bud. But this is only for practical reasons—not legal ones.