Oh, that brings up another point...Why are the CHISS involved in the Sith Empire? What? They are like an uber xenophobic group that hates being controlled. Thrawn was an OUTCAST from chiss society. Weird.
Chiss pragmatism overruled a hopeless idealistic last stand.
Remnants of the Sith Empire after getting their *** kicked on Korriban at the end of the Great Hyperspace War reconstituted in the Unknown Regions, and began an expansionist campaign. They ran across the Chiss, and gave them the usual "join us or die" speec they gave everyone else. The Chiss said "ok, we'll join, but we've got conditions".