《老人与海》里有这么一段：

I can do nothing with him and he can do nothing with me, he thought. Not as long as he keeps this up.

这里我对第二句话句首的not的用法感到非常疑惑。还请各位老师解惑。

我读到这里的时候感觉这两句完全可以写成一句话：

I can do nothing with him and he can do nothing with me, he thought, as long as he keeps this up.

这里我将he thought理解为主句，I can......with me理解为宾语从句提前，as long as ...up.状语从句。

不知道这样的理解是否正确？