He helps saves the world, does more work then the chief, and gets all the ladies, but
Doesn’t even get to be shown in the halo 4 trailer, or I don’t even know if he’s even in the game
It is confirmed he isn’t in Halo 4, he servers no purpose in the Halo 4 story, he isn’t on the Infinity and he isn’t on Requiem.
He’s busy with matters on Sanghelios, namely a massive civil war.
The Infinity helped the Arbiter with the rebellion. I personally why Karen Traviss had to go and throw away everything that the Arbiter worked for. At first I thought that the majority were still with the Arbiter. Then my hopes were crushed when I saw the Halo 4 visual guide. Maybe he will come back in Halo 5.