I don´t see the CSA as clean slat. After all they control the state goverements in the Rust Belt since several years and they are the initial basis of their power.You keep missing the point, I'm not discussing the leadership of any of the factions, all of them, even New England or the PSA are ideological to some extent, I'm talking about the structure of the government.
The Feds, New England, the PSA and to an extent are ideologues operating in and restrained by a non-ideological system of government, much like the US today, the CSA is a clean slate, fresh start ideological system of government with no checks and balances.
It's like the difference between Allende's Chile and the Khmer Rouge, one was takeover of an existing state the other was Day Zero.
McArthur is the clean slate, replacing the entire political system through his person.