The Spiritual Church forbade high-level organizations in the Central Continent to interfere with those of lesser power, as in the case of the Flaming Empire with the northern region of this continent.
In this case, while one side had Spiritual Saints, the other had as their highest level specialists only people at the peak of the 6th stage of cultivation, Spiritual Kings.
Because of such a discrepancy in terms of strength, even small organizations or mid-level individuals in the empire could wreak havoc in the Minos region, potentially disrupting church business in such a place...
Because while it was unprofitable for experts from that empire to settle here, it might be profitable for some to oppress, enslave, or otherwise exploit the entire Central Continent's north.
That is, by joining all the local resources of this part of the continent, there would undoubtedly be enough wealth to support projects elsewhere!