Sulu blatantly disregarding Starfleet orders to help Kirk and the others on the Enterprise. He may now be The Captain of the other ship, but he's still part of the crew.
- An episode from the Voyager series adds a little extra heartwarming for good measure.
Sulu: You'll find that more happens on the bridge of a starship than just carrying out orders and observing regulations. There is a sense of loyalty to the men and women you serve with; a sense of family. Those two men on trial... I served with them for a long time. I owe them my life a dozen times over. And right now they're in trouble, and I'm going to help them; let the regulations be damned.
Tuvok: Sir, that is a most illogical line of reasoning.
Sulu: You better believe it. Helm, engage!