Are you sure? Post 9/11 the CIA decided they needed to be in the business of kidnapping and torturing. They didn't seem to have any trouble finding employees to do it.
Soldiers need to kill people, but you don't want sociopathic soldiers - you want the opposite: Someone who can handle their emotions, not someone who hides from them, runs from them, or tries to bury or ignore them. The latter are not stable or reliable under stress.