We a re to be humble-minded and unselfish, and this is what it means to imitate Christ. If we look carefully, WWJD really is a form of behavior modification. That wasn't the answer the TV preacher gave. Jesus would not do. Sin, however, is more than acts of commission.
Sin also involves the omission of duty.
Failure to love God with all our being and likewise our neighbor as ourselves is transgression as well. This brings me to the crux of the matter. Jesus would fulfill all righteousness. Jesus would fully obey God. Jesus would as the last Adam, not fail as the first Adam did.