But even if Sarah Brown had turned around and said "I'm not running, because Shannon Rowbury should run", it wouldn't have worked out like that. Rowbury and Simms didn't email USATF and USATF hadn't listed her for Worlds, as per the World Championships criteria and deadlines. If Sarah had refused, there would have just been one less US athlete in the 1500.
There was a series of mistakes in that case and they aren't really comparable.