The use of "went missing" - to me anyway - says that the reason for a person's being missing is unknown as in any one of the circumstances you stated above and also includes a soldier's being concussed and simply wandering off in a daze/haze. A kind of battle amnesia? I would infer there is a slight - very slight - chance the soldier might turn up later(possibly with a head wound)with no memory of where he had been or what he had done.
As to "went extinct" I would infer that the reason for extinction is unknown : loss of habitat; killed by predators; drought, etc.
We do seem to get our dainties all in a twist when the language changes, don't we? I have several peeves but I've learned to shrug them off when encounterd because some are transitory and sanity soon returns. As for those that take root .... well what can one do ? (Sigh)
