Gentleman, I get your point now about fear of death. But you can be suidical while still being fearful of death and unable to actually kill yourself. So maybe people who actually manage to kill themselves would, in other conditions, be the ones who would risk or sacrifice their life for something else, because they are genetically unafraid to die.
But "suicidal disposition" isn't interchangeable with "unafraid of death".
I can't read any of those papers since you have to pay for them or something.