Check out the listing here:
After discussions with members of Video Game Memorabilia Museum, the community came to the conclusion that this is, indeed, an authentic prototype. VGMM member known as "Fall Moon" appears to have been the winner of the auction, further proven with the photo shown below with the plush being held with white gloves. (This photo was never included in the auction.) Fall Moon had made a post stating they had plans to have the plush cleaned and sealed to preserve it. Sadly, any additional posts they made on the matter (as well as the gloved photo) had been deleted from the thread in the Facebook Group.