I guess he just doesn't care that much about it... Or maybe my little Michael/Kimmet theory is actually true, and now Kimmet's sitting all alone on the pink mushroom cloud they should have shared...
Nah, I just think he doesn't care about it. He's probably thinking more about how to get through all the shit that's happening around them. Then again, they need to repopulate the earth at one point, after all there's only about 20 left that we know of...