I don't think Masi was deliberately trying to manipulate the race in favour of Red Bull or Max, but where 'rules' are open to interpretation they are not really rules, are they? As things played out, the decisions made clearly did favour one team and driver, and ultimately decided the championship.
While it might have looked like a 'race' on track (or at least more than driving behind the safety car) anyone who watches F1 understands how much of an advantage new v old tyres have. It wasn't really a race, and as soon as it restarted there was only going to be one winner.
Given the stakes, it was one of those unique situations where the team with nothing to lose had the bigger advantage of being able to throw the dice with strategy easier than the team in front. I still think Mercedes got that strategy wrong and could have pitted Lewis twice and still had the advantage, if not the track position. It's easier to say in hindsight than in the heat of the race though.
A further appeal would have done more damage to the sport than good, as would any decision that changed the result. I do hope the FIA learn from their obvious mistakes and make it much clearer what are rules which must be followed and what guidance is open to the race directors interpretation.
We won't have long to wait for 2022 and some pretty big changes to the cars, so all we can really do is hope for another close season like the one we've just had, hopefully with a cleaner end and a little less controversy.