I doubt Gaius is out for revenge on the Warrior of Light - by his philosophy their way was right, so as long as he's not hypocritical about it he has no reason to go after them.

The Ascians, on the other hand, he has plenty of reason to go after - Lahabrea lied by omission in regards to what the Ultima Weapon was capable of, and the reveal he was effectively little more than a tool to the Ascians probably pissed him off something fierce. If he knows the Ascians have a hand in the Imperial government that just gives him more reason to go after them, though whether or not he's aware of just how far the corruption goes is another matter.