>>717767691
>>717768343
Let's check Tau lore
It says that the Tau are frustrated by the Imperials' tendency to backstab them during negotiations. The Tau are gradually taking a hard line against Imperials.

Okay lets open the new Black Templars codex.
Page 9 says that being diplomatic with aliens is anathema to their chapter. They would rather lose than ally with Xenos.

>>717768389
Lets check some Drukhari lore.
It says that the same Drukhari group that scammed the Tau have scammed the Imperials using the same identical scam.
Moreover, Tau lore says that they just entered galactic superpower status.