I’m not sure every fact here is confirmed, but here is my understanding.

The path of the hurricane has been known for days.

Mets offered to adjust games, potentially including neutral site. Of course Braves declined as they wouldn’t want to give up home field.

Braves did not choose to move game up today or to move a game to Monday when they were both off. Home team gets precedence in weather related decisions

MLB did not choose to override Braves decisions or make any proactive decisions of their own. Not sure what the precedent for that decision would be.

Now, as anyone who follows the weather has known would happen for days, the rest of the series is postponed with no action taken until like an hour ago.

MLB is saying that if playoff teams are not locked in by Monday, potentially both games will be played on Monday.

If playoff teams are locked in but seeding is not. Manfred can make the call for what games (if any) happen on Monday.

In summary, if AZ loses themself out of the playoffs, and then Manfred makes the decision to give the 5 to the Mets and the 6 to the Braves, you can be sure that both teams would be livid. Nobody really wants the Padres or dodgers in the wildcard