You can define Rules to determine what are members of an audience. There is a "Member Of" Operator, but no way to define "include all users that are NOT part of an AD Group, or Dist Group or SP Group".
How would I do this without throwing code out at?
I'm sorry, but you can't. The whole mechanism is based on the principle of inclusion, not exclusion.
The only way I can think of to possibly make this work is to make a timer job or a scheduled task to fill a SharePoint group based on an AD-query to include all the people NOT in a group, base on audience on that, and compile it. But that's not what you want, I know :-)
