Tony does spin out of control and fights his best friend because he’s a drunken mess… except he’s dying. He already gave Pepper his company and is now entrusting the Iron Man suits to the one person he can trust: Rhodey. Tony brawling with Rhodes isn’t just a dispute between friends. Tony was testing Rhodes to see if he was willing and able to use the suit to fight his best friend if need be. In one go, Tony was training, teaching, and evaluating Rhodes’ suitability. Brilliant. War Machine was planned by Tony, who thought he was going to die.
All of which lends new meaning into Tony’s line to Rhodey earlier in the movie: “You gotta trust me. Contrary to popular belief, I know exactly what I’m doing.”