Why Ben Can't/Couldn't Kill Widmore

Maybe the island(or smokey or jacob or mystery dude) won't let Widmore die just like it wouldn't let Michael die until Widmore has performed some act. Maybe thats why Ben couldnt kill him.....he may have tried to or had someone else try to and figured this out.

If memory serves, Christian appeared and told Michael that the island was done with him right before the freighter blew up. Perhaps Widmore will go out in a similar fashion in season 6.

The island may also be responsible for Desmond's bulletproof shopping bag.....or maybe, like most guys, Desmond doesn't know how to buy groceries and he bought some stale rock hard bread and a bunch of frozen microwaveable meals.

cool theory. ben couldnt kill penny either. she was being protected. if charlie hadnt come on deck ben wouldnt have wasted time in pulling the trigger.

we dont really know that these people cant die. Ben hasnt tried 2 kill Widmore, i think he was going to let him live so that he could feel his pain after he killed Penny. and we have no proof that Penny cant die either, Ben just saw he with her kid and ultimatly decided not 2 kill her. If ben had pointed a loaded gun at widmore and fired and it stalled several times like the michael situation when he tried to kill himself then i'd b convinced but as far as i'm concerned widmore is fair game for Ben if he did decide 2 kill him.