judging from the points i highlighted in red, i believe your
brother is too impulsive in his actions.
firstly he should have radioed for help. secondly, from your
descriptions i believe the soldier isn't really dying, maybe just
dehydrated. thirdly, i find it hard to believe an abandoned car in
working condition with keys still inside it. i think it's more like
someone park it there and went off for a while.
this is considered a serious offence if the dehydrated soldier
isn't in critical life threatening condition to justify youir
brother actions in stealing the car plus failing to report this to
his superiors.