This didnt start at the charge. If you see what happened the play before while Milwaukee was on defense.. MO and Giannis went up for a rebound. I don't know if MO stuck his butt out or whatever he did. Giannis fell. Then Milwaukee goes on offense. Giannis is still behind trailing and he comes charging up the ball is fed to him. Hes full steam and mad at this point and then MO tries to catch a charge. I don't know if MO said anything else but Giannis had words for him. And then the headbutt came.
They reviewed the charge. MO leaned left to try and get it thus committing a foul. But too late by then Giannis had head butted him.
But to me it all started on the rebound.