I was stationed at the same base a decade earlier prior to leaving the Marines and finishing my bachelor's degree and becoming a law enforcement officer. It's true that you can be assigned seemingly at random to provide security at a crash site, or in my case I was assigned to identify aircraft parts and their condition at the time of the crash. For example, I could point out an aileron controller and the attached hydraulics plus backups and even triple redundant safety systems then tell FAA investigators if the ailerons were being used to trim the aircraft, or if the flaps were fully extended etc. I knew this information as part of my training and specialty was everything electronically controlled or actuated in several platforms. I should add that having a good basic understanding of avionics makes it fairly easy to know quite a bit about almost any aircraft.
I never got sent to anything like the young man is talking about, but helped investigate a couple crashes of attack jets and one executive transport aircraft. In later years while I was assigned to CID I ended up going through a wide variety of training that included skills I'm glad I never needed, such as train crash investigations.
One interesting single engine multi-seat airplane crash I responded to with my CID partner involved a very wealthy man who had previously been a victim in a burglary I investigated and solved. It's still funny to remember, because I caught the burglar after he activated the EPIRB rescue beacon he stole from an aircraft hangar and it led me not only to the apartment complex where he lived, but it was so sensitive it led me to his bedroom closet, top shelf!
There wasn't much his attorney could do to help his case after that.
Aside from my tangential detective stories the owner of that aircraft was flipping out at my partner and I because we were walking around his munched airplane as if we were there for a search warrant. He had no true conception of what a law enforcement officer does, obviously, but his behavior definitely indicated he was up to something more than trying to fly from Oregon to Idaho to deliver a radio. You don't need to be a detective to feel the vibe of a man worried about being caught, especially when he's barking orders and saying nobody can search his airplane when nobody was asking, and neither of us were even interested in him or his airplane.
In any case he was just another customer who hated us even after we successfully cleared both burglaries of his poorly protected aircraft hangar. The only cool thing about working his cases was the P51 Mustang he owned that was kept in his hangar.