Is there a source that it was definitely claimed? The BTC have moved, but the site notes "[i]n 2018 we will likely reuse most bitcoins for other projects", and the transaction (splitting into two amounts of 9BTC and ~1BTC) aligns with this Tweet from December:

> PSA: the bitcoin piñata will be reduced by a large amount, the owner who lend the 10 btc wants to spent 9 on useful projects

https://twitter.com/h4nnes/status/939430639576715264

From their site:

"This challenge started in February 2015, and will run until the above address no longer contains the 10 bitcoins it started with, or until we lose interest. In 2018 we will likely reuse most bitcoins for other projects."

So I'm not sure what happened frankly.