Unless there's a law in Washington that forbids a property owner from willfully approaching a trespasser, or otherwise requires a property owner to flee in the presence or suspected presence of a trespasser, it seems to me that the issue is whether or not the property owner was acting in self defense at the time of the shooting.

Not sure how a jury would see it. Seems to me our nation is moving toward the general notion that absent running away and hiding under the bed that the victim of crime is complicit.