From The Neo-Anarchists Guide to Real Life (from SR2) page 46...
"...HTR (High Threat Response) teams are made up of seven members who fall into two distinct categories of training. Three medical personnel, trained and equipped in much the same way as the personnel who make up SRTs (Standard Respone Teams) and CRTs (Crisis Response Teams), provide medical care to the client."
"The other four members of the HTR team function as 'threat support personnel.' This group protects the medical team and the client from hostile action during the pickup. Though all DocWagon personnel receive medical training, threat support personnel receive a majority of their training and experience in combat."
Regarding SRTs, page 45...
"An SRT includes the personnel and equipment required to treat and release victims of minor accidents or injuries. In more serious cases, this team stabilizes the victim on-site, then transports him or her to a DocWagon clinic for additional care."
Regarding CRTs, page 45...
"...Incidents requiring a Crisis Response Team (CRT) typically include large, multi-vehicle accidents, fires, earthquakes, gang wars, and so on."
Regarding leadership roles in DocWagon teams, page 45...
"...In an environment with high active threat, however, DocWagon standard operating procedures (SOP) authorizes an SRT to attempt service, but nothing more. The team leader decides how to handle the situation, and usually calls in an HTR."
I mentioned this last bit to emphasize the possibility that our intrepid 19 year old was likely a "threat support" person and also a team leader in that role. Given that (somewhat unlikely assumption) then it's perfectly reasonable that he called the shots.
Also of note, the above-quoted out-of-print book is available as a PDF download for $8 at
BattleShop.