61.15 is "Offenses involving drugs and alcohol". This does not sound like an offense involving drugs and alcohol. (e) of this regulation is what pertains to the motor vehicle actions, but again, the context is offenses involving drugs and alcohol.
This seems pretty clear to me:
https://www.faa.gov/about/office_org/headquarters_offices/ash/ash_programs/investigations/airmen_duidwi/
If you wanted to be absolutely sure, you could contact this office:
If I have more questions, how can I contact your office for more information?
You may contact an investigator Monday through Friday, 8:00 a.m. to 4:30 p.m. CT, at (405) 954-4848. Please Note: You must send a written notification of your alcohol- and/or drug-related MVA. You may not give this information by telephone.
They aren't out to do secret stuff like wiretap people or do phone tracing. They would answer a question just as CAMI or the Regional Flight Surgeon would. I had a question about required paperwork for asthma stuff (which I don't suffer from, but gotta go through the paperwork loop) and they were absolutely helpful. I can't imagine anything different here. You would, err your friend would just be an airman calling and asking a question about whether an action is reportable.