Folks, step back one moment. Forget liability--civil or criminal.
If we're talking about the FCC, the letter goes to the licensee's fitness--a vague term of art used to determine who has the money, community standing, political power, and most "i"s dotted and "t"s crossed in their application. But fitness is a continually judged pattern of conduct, concerning operations, programming content, community reception and service, complaints, and the like.
It may be affected by liability for on-air contests. Or there may be no liability at all and there's still a licensee fitness issue.
Whether this contest was a problem before isn't an issue to the FCC. The fact is, the contest happened, the management of the station knew it was happening, or was naively ignorant, or was willfully unaware of what constituted the contest. This may be a matter on its own--which is probably is--or it may be one of numerous issues with the licensee of the station. Running by the FCC's own database, there is an outstanding renewal license, with at least one proper Objection and Motion for Denial from the public.
What's to say that this won't spark more letters of objection...or that the FCC won't review anew the status of Entercom's renewal?
Remember, we're dealing with the FCC's own procedures here, not courtroom process, legal standards, or common sense saying "don't do that". We're talking about the Commission finding that the licensee knew how to operate a radio station, and putting the faith in that station's ownership and management that it knew what it was doing.
We'll see whether that results in anything to Entercom, but for now, EVERYTHING is on the table and can be looked at to determine whether this station violated the public trust and public interest in conduct itself in this manner.