Jim can understand completely. From what he heard about the other Khan's invasion of the Nexus, the captain has his own concerns about a powerful enemy finding a way into this place. And there's a reason he is still the only one from his universe to have a PINpoint. It's good to have backups, but it doesn't entirely outweigh the increased chance that it could fall into the wrong hands eventually.

He's made too many mistakes to take something like that lightly.

"Make sure you don't lose it. I don't know if magic can tether it to you, or something..."