The trouble is that Michael Masi intially said no unlapping, and then changed it to only the cars between LH & MV just before the safety car comes in. Therein lies the problem(s). The confusing messages AND the fact that only the cars between the leading 2 were instructed to do so.
Rule 39.12 - "If the clerk of the course considers it safe to do so, and the message "LAPPED CARS MAY NOW
OVERTAKE" has been sent to all Competitors via the official messaging system, any cars
that have been lapped by the leader will be required to pass the cars on the lead lap and the
safety car."
No where does it say selected cars, so why were the cars behind MV not told to unlap?
"This will only apply to cars that were lapped at the time they crossed the Line at the end of the lap during which they crossed the first Safety Car line for the second time after the safety car was deployed." i.e those behind MV should have been instructed to pass as well.
Having overtaken the cars on the lead lap and the safety car these cars should then proceed around the track at an appropriate speed, without overtaking, and make every effort to take up position at the back of the line of cars behind the safety car. Whilst they are overtaking, and in
order to ensure this may be carried out safely, the cars on the lead lap must always stay on the racing line unless deviating from it is unavoidable.
"Unless the clerk of the course considers the presence of the safety car is still necessary, once the last lapped car has passed the leader the
safety car will return to the pits at the end of the following lap. If the clerk of the course considers track conditions are unsuitable for overtaking the message "OVERTAKING WILL NOT BE PERMITTED" will be sent to all teams Competitors via the official messaging system."
The problem this brings is of course that the race would have finished under the safety car and there's no way that the FIA wanted that to happen... so they deliberately ignored their own rules which leads to MAHOOSIVE precedents for next season unless there's a major change to the rules in the meantime.