Having read the explanation isn't it the case that the VAR official didn't realise the goal had been disallowed? So essentially he was working under the assumption that the goal was given and believed he was checking to see if the goal was disallowed. He then saw the goal was onside, told the ref that the check was complete and the on field decision stands and only after they restarted did they realise their cock up.
Huge breakdown in communication between the officials, inexcusable.