Totally expected that an Allegheny County policemen would tell you to just lock up the pistol in the lock box before you come onto Airport property.
Yes, Allegheny County does have an ordinance that prohibits firearms on airport property, but that ordinance is in violation of the Uniform Firearms Act, and is thus invalid.
Allegheny County refuses to amend the ordinance (they try to pass it off to the Airport Authority). The Airport Authority won't even respond to any correspondence on the subject. And the County Police continue to post on their website that firearms are prohibited on airport property.