I would interpret "self sufficient" as:
* Having my bike in good repair and bringing spare tube, pump/CO2, cellphone/ID, wallet, water, food
* Knowing how to handle flat tire, call for SAG for anything much beyond that
* Adult with common sense, not an individual requiring supervision

Leaving somebody with a head injury by themself -- unbelievable.
A damaged helmet or head injury is "RIDE OVER".
1 or 2 people should stay with the injured until SAG/ambulance arrives; and watch after the bike.