My impression was that there wasn't a League of Bullies, but that SPHEW might have brought one into existence.

That is, while most of them might not proudly label themselves "bullies", they share a common quality: people who have been embarassed by Granger & co. As it became clear that they would need to band together to redeem themselves, a loose coalition was formed.

So I think of it simply as a bunch of otherwise unaffiliated individuals realizing that they have a common problem and goal, and temporarily banding together to achieve it. Which seems at least more plausible.