I've Seen Plenty of Talk About Azir and....
...everyone seems to forget that there are only five people existing in the world that are aware that the slaves were freed and Azir is against slavery. Remember, Azir was destroyed minutes after freeing the slaves, as was most others. This means Azir, Sivir, Nasus, Renekton, and Xerath are the only ones aware of this. Everyone else just thinks that the emperor is back, and mind you, there were slaves. So no, Azir wasn't evil.