"You have a lot to learn about life and death, James," Rebekah said rather calmly. A fourteen year old wasn't likely to have the understanding of the universe that someone as old as Rebekah did. Life wasn't fair so why would should death be? And the blonde vampire felt she was being rather kind by letting Clint be to enjoy his time with Natasha.
Of course, should the time come (and it likely would) that she would need his assistance again, she would have no trouble finding them here and using James as a hostage if need be. Hopefully it wouldn't come to that but with Clint you never could be sure.
And as if he was nothing, she walked away from him. Because he was nothing.