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?
I know if my next of kin got a random weird email or message on social media asking about bitcoins they'd either have no idea what you were talking about or just ignore it. They'd also probably ask me if I knew anything about it first before responding and if I was alive and holding 250 bitcoins I'd probably just tell them to ignore or deny it.
I had several letters professional translated asking to make contact to provide information, not to immediately reclaim the bitcoins. There also seems little reason to ignore it because I stated that his estate is owed some money (which it is).
That would possibly be even more alarming. People tend to ignore any letters claiming that they're owed long lost money. 99% likely scams and most people would just disregard it.