I didn't read the link you've posted but I'm guessing that the drive has a few (?!) bitcoins on it.
Hard drives are pretty rugged, and as long as they are not spinning, they can take quite a bit of abuse.
They are also reasonably well sealed, so unless it's submerged in water, chances are good that the innards are OK.
They are also made of metal, so he can use a ground penetrating radar to look for metal objects of a certain shape and size.
I think he has a fighting chance.