Just for the purposes of illustration, I hope everyone forgives the double post, but take a look at this:
As you can see, Medaka did, indeed, consider not having a reason to live as a credible option, because it made her feel better.
Only, when she was given an actual finite goal, that made her feel even better.
So yeah, this definitely does not seem like the Kurokami which was hopelessly in-love with humanity at age 2. She was just a kid trying to feel better.
Notice how she became "her" after Zenkichi gave her a goal.