The policy at one of the services that I worked at was that they'd give you a lunch period. You couldn't be disturbed to do transfers or minor responses. But they could call you out of break for major responses (like cardiac arrests). I imagine their policy could be similar. Where instead they can get notified about a major response and can choose to end their break or not. Sounds like the EMT thought it'd be a good idea to respond since the person was dying, but the medic wanted to stay on break.