I think you are overthinking the Zen. From what I understand, you're supposed to be mindful of the things going on with no intention. Does that mean being emotionaless or being observant of the emtions you're feeling at the time of being mindful, I think is the right question to ask.
Overthinking the Zen is a terrible thing.
In the seated meditation (as well as the corpse pose) that I do in yoga (Kundalini)- you acknowledge the thought that interrupts, then let it go, by returning to a focus on your breath. Always, always - back to the breath.