With zMaul teams getting lots of stealth, Thrawn is going to get beat down. If you have him maxed with fast mods and zeta his unique, it'd probably be good. He won't beat most of his Sith teammates on his first turn, but as long as he goes before the other team, he can Fracture someone and the stealth on most of the Sith is going to be like a soft taunt for Thrawn. Lots of counters.
Of course, EP is the only person on your list who is an Empire character, so the rest of Thrawn's unique is mostly wasted, but whatever.