Makes sense up until the part involving Chief's trailer. In it, Chief is talking to himself, not acknowledging Locke until the very end. My thinking is as follows: In the wake of Cortana's demise, Chief has had his humanity thrust upon him. Unfortunately, he can't adjust. He's grown so used to war after it being the only thing he's known for almost all his life that he can't stand life without it. Using the anomalies as an excuse to get back into action, he starts investigating, possibly teams up with Mendicant Bias. Bias, after seeing how humanity is acting, uses Chief to gain access to a means by which to attack humanity AND stop the anomalies. Bias betrays Chief, and the UNSC blames Chief for the ensuing disaster.