Notice the date of original publishing is April 19th.
MR posted that article here containing the engineers name, etc.
https://forums.macrumors.com/threads/900754/
So gizmodo didn't add the names behind the event at a later date.
Not clear, but not definite proof that it wasn't a prototype. The external case had codes that Apple uses for their prototypes. Evidence like the codes and how OS X and iTunes behaved and shown on the screen was showing it was a real Apple prototype. And they still went ahead and published it.
They said in their own words they had the prototype for a week. So it wasn't like they were publishing as they were going on with playing the device. They knew it was real when they started to publish the articles. So they willingly published Apple's trade secrets. Even if the DA doesn't charge anyone with a crime, Apple can still sue gizmodo into the ground for that.