But if there is a back door, doesn't releasing it as open source open the possibility that China's or Iran's equivalent of the NSA will audit the code and find it too?
That's why they should stop doing that. We aren't the smartest country on the planet anymore.
In which case the NSA say "Oops, it was a genuine mistake. Sorry." With 200,000 lines of code, there will almost certainly be unintentional security holes that haven't been found.