The T'au's idealistic "Greater Good" is contrasted against the Genestealers' biological imperative, which also masquerades as "Unity" and "the Greatest Good".
This inquiry likely refers to the short story titled " The Greater Evil " by Peter Fehervari, published by Black Library .
The expedition discovers that the "civilization" they intended to convert is actually a front for a Genestealer Cult known as the "Cog Eternal". The title, "The Greater Evil," plays on the T'au philosophy of the "Greater Good" —suggesting that the horrors they encounter are a dark mirror of their own expansionist ideals. 3. Key Themes & Philosophy
The phrase "the greater of two evils" is also frequently used in fan discussions regarding the or Imperial vs. T'au debates. Fans often argue whether the Imperium's brutal authoritarianism is a "lesser evil" compared to the total annihilation offered by Chaos.