The main reason the result should be rolled back to the last racing lap is Mercedes know the rules and based their decision on not pitting Lewis on them.
They knew that if the lapped cars were allowed to correctly unlap themselves and then the safety car comes in at the end of the next lap after the last lapped car has passed the race would finish behind the safety car. Lewis would win.
If the lapped cars were not allowed to unlap themselves then there would be 5 cars between Lewis and Max and Lewis would probably have held out to win.
What happened was neither of these scenarios but a totally fabricated restart that was against the rules that no team would have expected and so could not base their racing decisions on it happening. To say that only allowing the five cars between the leaders had no baring on the result is incorrect.
Mercedes have every right to appeal the result