Same reason Fraacta and Maakrep are in CA. Evil Tohaa. We know the Spiral Corps have agents from the Triumvirate (sp?) among them, so, lots of room for double dealing.
That makes no sense because Tohaa are already evil. You mean good tohaa because the only good ones are within the Combine Army. :P
I have an idea. Two Shasvastii or Ariadna full-camo lists. There are no deployment restrictions, no deployment zones. And no knowledge of which camo marker belongs to each unit... or player. You may be deploying the enemy force the whole time and not know it. (Hardcore version: camo marker ownership gets revealed not at the end of deployment phase, but at its first activation). It's double agents all the way down.
Are we sure Grief Operators are Tohaa? I can’t find any additional info on them. Maybe they are just another Merc like Cube Jaegars and Warcors. I mean there are planty of merc units in human and CA lists why not one that crosses and works with the tohaa and CA as well