answer:There is not a one for one correlation between seeing multiple deaths and suffering from PTSD. Those prepared for the stress of a traumatic event are less likely to have PTSD. Also, people with a lot of social support tend to recover from stress and not get PTSD. And lastly, one factor in experiencing PTSD in a military or disaster situation is recognizing the humanity of the enemy or the victims one is helping. Kirk on the other hand would not ascribe humanity to most of his enemies, especially Klingons. But he recognizes the humanity in Vulcans, which is why he grieves for Spock.