A white-hat developer (someone who hacks for good) noticed the problem with the abcya.io domain. To solve it—or perhaps to prove a point about how easy it was to trick kids—they utilized GitHub Pages.
But here is the truth:
This forced the actual ABCya company and school IT administrators into a difficult position. They couldn't easily block GitHub without breaking computer science classes, but they couldn't let the unblocked clones run wild. abcya.github