github.io is on the list. *.github.io is not. They are different. The rule only goes one level down. The github.io rule means foo.github.io cannot share with b

github.io is on the list. *.github.io is not. They are different. The rule only goes one level down. The github.io rule means foo.github.io cannot share with bar.github.io. However foo.private-org.github.io can share with bar.private-org.github.io. The *.github.io rule would prevent that.