The Kroot are more like Tau in their tactics than many people give them credit for.
The Tau do not simply go around finding anyone/thing to join the Greater Good, they have to have something to offer for Tau society/military.
As an example: The Orks, even if they
did want to join the Tau empire would be rejected because of how unTau-ish they are. Not only are they barbaric, but they think and act in a way that the Tau do not like; unpredictable, brash, brutal, like personal glory and use attrition to beat down an enemy. All of these are an antitheses to the Greater Good. The Orks cannot be reasoned with... but more importantly the Tau
WONT reason with them. The Tau just don't like Orks
