I guess his friends or family could have found the wallet and finally cracked the password
It is also possible that his family sold off his computer/device that he was storing the forums BTC on, and whoever purchased it was only recently able to crack the password/encryption used to secure the BTC.
But then why send $2,500 to his old dead wallet?
Where did he send $2,500? It just seems to be one transaction of the full amount. Did that 250btc end up in any addresses previously associated with him?