Yes, things die.
I remember some mystical moments spent at the Mariposa grove.
There are factors I consider and sometimes I call certain deaths "premature" - meaning wrong place at the wrong time. Cancers for example, or cluster bombs aimed at precise targets within a civilian compound.
Coastal Redwoods, Port Orford Cedars, and both sequoias along with some early logging habits of clear-cutting right up to tall stands are susceptable to new stresses like winds, base erosion and the like so many of the open logged areas show examples of hedgerow losses, domino-like felling long after revegetation has started. These two giants however look like a combo of diversion of natural run-off and like TreeTex said, got to the end of their lives.
I guess the gain here would be to see if they contract-out for bids on lumber recovery or let death do it's thing - rot and feed. I hope they let them die in peace.
At the mimimum, as far as people go, it's another thing to think about when stealing-away and climbing one of those magnificent giants in cognito - there's a chance you too, could find a premature death. What a way to go though, eh? Like getting eaten by an Orca.