But wasn't that the point? To risk their lives for knowledge, in this case knowledge not just for an unusual phenomenon but for a "dead guy" who in the space of an hour became all too real to Seven and Tom and Chakotay as they listened to his voice and his stories.
That's why I absolutely love the ending, despite some people's interpretation that Seven was upstaging the corpse at his funeral.
SEVEN: The Yankees, in six games.
To me that line and Tom's smile meant that the "dead guy", even if only for a few moments, once again lived for these people. Once again "mattered" to his community, beyond just being a name and a mission date.