Tied for 16th. place.
Sad but true. This is not the same as his 15th place at the 2007 Mr. Olympia contest, where there were 24 competitors, none of whom were placed after Will. They were all "16th" in the manner you describe, you could say.
So Will's 15th that year at the Olympia was a meaningful placing. Especially given that he was, what, 46 years old at the time?
Could you imagine how freaky Will would look in person? He would easily be the largest and most muscular man in any gym 99% of the time, literally anywhere in North America. Yet despite this, by Arnold Classic standards, we are saying he looks bad. Perspective makes a difference here. He will place last, as you said, but he is looking freaky for any age, let alone a 55-year-old man.
Oh, and I fear for his health.