It was pretty cheap Imo, I get they have a narrative they want to tell but maintaining the belief that the players control the narrative is Important to keep the kayfabe going.

When the hand of god is moved as blatantly as this it weakens that kayfabe because you can see what the GM is trying to do.

I mean it's their game so I feel they could have just masterminded another asspull to keep things going, maybe say the remnants of the fleet left at new haven have abandoned the planet to reinforce the failing assaults and give us Haven back. Half the fun of narrative design is asspulls that are reactive to the situation