I feel most people are fundamentally misunderstanding what forking means.

Generally, forking means making a copy and modifying it.

Github, however, seems to define "fork" as just making a copy.

So, in fact there is no "TOS violation". The license forbids making a copy and modifying it, while github requires that you allow making copies. There is no conflict between the two.

Even if it were, just having a license that contradicts the github TOS is not a TOS violation (unless that is separately mentioned somewhere).