The antidote seems to be for the NSA to maintain a security report for each discovered zero day. If it ever leaks, they can send the target company the report, which explains both what the exploit is and how to fix it.

That seems fair enough. The NSA needs to exploit flaws, but they can be a bit less evil about it by being ready to fix them if necessary.

That doesn't solve the fact that NSA's competitors could find and exploit the same flaws, or that sometimes it's hard to tell whether any leaks have happened, but it's an improvement.

At the end of it, it's hard to seriously argue that the NSA should stop exploiting computers. It's their role. We need them, just like we need a military. But we can think of ways to reduce the impact without getting in the way of their job.