There were too many experts from the World King Planet who had joined the cosmic overlord army. They couldn't be controlled.
In the face of this kind of thing, the World King Planet only had to ensure that the people who walked out of the World King Planet didn't point their swords at the World King Planet itself in the end.
Although the cosmic overlord army was a shit stirrer in the interstellar war, if it stirred up the Contaminated Land and the Worm Race Mother Nest, World King Planet would also be happy to see it.
As long as it didn't become the enemy of the World King Planet in the cosmic battlefield, there was no problem.