Maybe an unidentified aircraft but certainly not object .
The official report then didn't state anything other than killed while flying and hasn't changed, even now, as seen in the official USAF biography. News reporters took to the UFO slant to capitalize on the Area 51 craze. When I read it, I thought it was dumb and expected an official clarification which never came. Later, some tried to equate the unknown flying object to the F-117. Once the squadron's history was declassified, it was then corrected.
Strangely enough, the New York Times got it right (other than the MiG-23 type) in their May 6th, 1984, update on the story:
There are plenty of sources for the various MiG squadrons now that the information has been declassified. Lots is still missing though. Aside from the aircraft, there is the 'Petting Zoo' at Nellis with opposing forces ground equipment which included air defence. Again, lots is available in books and online but parts are still classified.
Nellis Petting Zoo
Find the SAM-6 at the Petting Zoo, and compare its missiles to those in the Trumpeter kit. Yet, they were made aware that the wheels and tracks were replaced but based on the Shilka's items.
Aberdeen Proving Grounds also had a restricted access area with modern Soviet tanks (then, would be Russian now) being tested. I have an album of film photos to scan from that unit. Some, like the UAZ-469, are done.