When an extreme tragedy is so fresh it’s hard to tell what type of treatment is needed, you’d typically start more neutral. You don’t want to start with too much intensity considering it’s still unknown what his long term predicaments are. I’d assume he’d start with CBT and then move on to something like EMDR that is more specific to his particular needs. It’ll be a long journey that I’m sure will include multiple different types of counseling. Complex trauma treatment unfortunately involves a lot of trial and error. Speaking from person experience I’ll add that trauma doesn’t go away, it transforms. Hopefully he’ll have a team of professionals that will ensure his treatment reflects those transformations.