Can someone help me understand how playing oldies (or any music format) is going to be an essential service to the "city of Covington"?
Let me try. You follow the rules put in place by the FCC for "1st aural service" to a community and you can move it to just about anywhere that isn't included in an urban designated area (as determined by the census). Even moving to an urban designated area can work if the town you are moving to has its own government, schools, zip code, fire and police services and businesses which sets it apart from the rest of the urban area. You can't normally move out of an area that is going to be underserved by existing aural services when you leave. The problem is what constitues underserved.
We all know that most of the music radio stations around here, even in Seattle, do very little by way of public service. Usually, they bury most of it on early Sunday mornings. So, really, who cares what city of license is on the FCC license. Whether it be Covington, Seattle, Tacoma, or Eatonville, it doesn't matter that much because you are not going to do much in the way of serving you community anyway. But the FCC has the idea in mind that you are going to "serve" you community with first aural service. Apparently, turning on a transmitter and modulating is considered "serving" by FCC standards.