My inner selfish self keeps telling me to choose monarchy. I would really love to make Vexx my prince and the belle of the ball. However, common sense dictates that peace and alliance requires genuine trust. Cursans have already lost their trust in the crown, with Orion following close behind. Enforcing authority over Cursa or even Orion would only deepen hostility and would further divide these societies, which means more destruction and decay as well as subsequent rebellions and coups. I agree with Damon that Cursa can't recover without continued support from Goldis, but aiding and funding the growth of a friendly society doesn't require supreme power. Instead, it can be arranged via bilateral agreements and charity.
If I had a third choice, I would let all planets decide whether they want idependence or to stay part of the empire instead of forthwith abolishing the throne. Regardless, I would prefer to sustain a constitutional monarchy with an executive monarch on Goldis. Even if all four surviving subordinate planets achieve independence, I think only Tilaarin is ready for democracy and a form of republic. Alicia and Zane will definitely need to rule Cursa as monarchs, but once married, they should have equal powers with joint and several liability, unlike in traditional kingdoms where the monarch outrules their spouse; otherwise, they can't keep the Crimson Dusk and the Azure Dawn together.
Then again, abolishing the throne may be necessary to clear the Peg'asi name and regain their credibility; after all, the coup happened for a reason. Its mere promise can help gain support against Zovack. Out of the two choices provided, I will definitely proceed with ending the empire.