Yeah, he's an asshole, but look at it from his point of view:
You're in charge of the biggest, most technologically advanced ship humanity has ever built. Thousands of people are on board. Then all of a sudden, the ship is dragged forcefully to a strange world and attacked by an unknown enemy. You and your crew barely survive, and there's an opening to retreat, report to command, and receive reinforcements. But a formerly MIA Spartan and his clearly rampant AI companion tell you to [i]stay?[/i]
Wouldn't you have the same reaction Del Rio did? I know Master Chief is a hero and all, but we don't know what the hell we're dealing with, and I sure as well wouldn't go in guns a blazing, unnecessarily risking the ship and the crew's lives.
And he gets removed from command for that. What the hell?
-
Well this jackass, Captain Del Rio, didn't use his head. The chief saved the -blam!-ing galaxy three times and the human home world once already. He DIDN'T need to order Chief to relinquish Cortana on the spot like that, he could have waited until they got home because clearly, they were in a bad situation, screw the UNSC regulations, lives are at stake. John is a seasoned soldier, a Master Chief, with the most advanced AI created by man at the time (even if it was going rampant). If John and Cortana have an idea, you might as well sit your ass down and listen.