After Boris was released, the Boris problem is expected at that time to continue.
Death Monarch plans of dividing the world again into ten realm actually alleviated this problem.
The reason why Boris become problem is because his influence over the Senators was too strong
His reform shakes the entire governance system of the Republic. If it was allowed to continue, the Republic could shatter and broke apart.
In the past such Republic that is broken apart is something that the world power like the World Government very much like to see.
But that is before.
Now, if the Republic disintegrated, the World Government would bear the brunt of having to deal four great powers.
And if these upstart manage to convince Pandemonium, then World Government would have no leg to stand on in the international community.
In the past, before the Fall, even if you are isolated, there are other countries you could do business with.