I believe we had a discussion about this before. This was my take:
The Destiny of Peace story could be a fun arc to flesh out. I personally think that the (corrupt) Vasudans politicians who were involved in this situation may have put up a token resistance afterward or made idle threats (considering that this story happened in October of 2335, 4 years before the Vasudan Emperor disbanded their corrupt Parliament). But with remnants of the Shivan fleet around, the HOL still a viable threat and losing 2 capital ships in the Manda engagement, fighting a war on 3 fronts would have been almost suicidal - spreading Vasudan resources so thin that the very survival of the Vasudan race could come into question.
In fact, this massive defeat could have been the very catalyst that eventually lead to the disbanding of the Vasudan Parliament 4 years later. The shady, back room deals that caused the loss of a viable home world and thousands of Vasudan lives, now uncovered, could have been the straw that broke the camel's back for the Vasudan people. Then, after investigations into the rout at Manda revealed the corruption, the public outcry could have forced the Emperor to act.