In order to join the Interstellar Colonization Council, one must become a Muta Person. This is a condition.
Of course, there may be people who were not Muta People previously but still joined the Interstellar Colonization Council, but Milton Cheney is clearly not one of them.
He is aware that everyone in the Interstellar Colonization Council is a Muta Person.
However, he doesn't know the specific process of how they transformed from Azure Star's people to Muta People, so he is somewhat curious.
In order to thoroughly understand the Interstellar Colonization Council and the Muta Civilization, Milton Cheney needs to get closer to them.
To be closer to the Interstellar Colonization Council, joining it seems like a good choice.
But there is another key reason.
That is, if he wants to explore the complete path of a Transcender in this world, joining the Interstellar Colonization Council is undoubtedly a shortcut.
Milton Cheney had begun brewing this undercover plan quite early on.