>Firstly, when Coop is presented with the mission to go through a wormhole to another galaxy he doesn't protest on the ground of possibly never seeing his children again.

He does, though.

Coop: "How long would I be gone?"

Brand: "Hard to know. Years."

Coop: "I got kids, Professor."

Brand: "Get out there, and save them."

And the very next scene is Brand putting him at ease by giving his word that he will solve the Gravity Equation by the time Coop returns.