Unfortunately, it does not actually show a photo from the Nimitz Encounter. It shows a photo from the Chilean Navy case, which was swiftly solved as being an A340 aircraft.
The Jesse A. Marcel Library (JAML) and Crop Circles Research Foundation near Montana City has placed this billboard along Highway 12 near Helena to call attention to the ongoing mystery of Unidentified Flying Objects.
“… something not from this world,” it quotes USS Nimitz pilot David Fravor.
Here's the original image for the plane from 2014. The very hot glare from the engines obscure the shape of the plane.
The radar track of the plane is a perfect match for the actual Chilean observations.
By contrast, the video associated with Fravor's statement (although taken at a different time) is this: