Legally possible (Score 1)

First off: I am a lawyer, but not admitted to the bar anywhere in the US, so things might be different there. Generally, his heirs / estate should be able to get that kind of information. It probably involves notarized letters, perhaps even a court order, but it certainly can be done.

As to his local linux box, unless he used encryption, that's fair game also. I see no moral problems with either.