No inheritance doesn't compel Apple to unlock that inherited property. Imagine it like a safe. You might inherit a safe but there is no obligation on the manufacturer to help you unlock it.
I say this as someone who has sadly had to explain to others a few times, that recovering encrypted files is nothing as easy as "busting it open" in the physical world.
This is incidentally why governments are scared of encryption, but IMHO users should be too --- it is very, very strong technology. Encrypting data with a suitably secure algorithm and losing the key means it is truly gone forever. You have to weigh that risk against the risk of someone else getting access to the data.