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?
Are you sure you 100% confirmed his identity or his next of kin?
I traced him back to his family home which hadn't been sold in decades. Whoever is living there now is either the family or the tenant of the family.
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).
His identity (name-surname) was well know or am I wrong?
Well, I guess so then. A related issue is that the name format in Spain (which that business reg. document is from) is different to Romania. Those documents could have been forged though and would only need complicity with his business partner (who strangely also refused to make contact after several attempts).