Explain the conditions for termination of an employee under the contract and the exceptions under Oregon law.
Unless there is wording in the employment contract saying otherwise, then they (or you, or I, or anybody) can indeed be fired for being stupid or arrogant. Or for driving the wrong color car. Or because our boss is having a really bad day. In Oregon, you can be fired for any reason whatsoever with the exceptions on the short list of prohibited reasons (race, gender, etc.)