Ehhh, i don't think that's exactly why he's doing it...
Ehhhh, I can count on both hands how many times I have stopped at wrecks... usually it's 1) I am the first person there, so I call 911 first to get the AHJ coming and 2) it's more than just a fender bender. But I don't think that's what OP's department does
What's the worst that can happen? after all, Oxygen is not flammable...
Sidenote: all of our spare oxygen bottles were stored in the non-insulated ambulance bay... it did get pretty warm in there too.
As I am reading OP's use case, his reasoning isn't the same as yours... there are quite a few volunteer first responder agencies that still respond POV to a scene. Call goes out, nearest people head to the scene, and someone goes to the station and picks up the transport vehicle. I'm not saying I agree with the practice or not, but in the rural (and some suburban and even urban) parts of this country, it happens more than you want to believe. While your use case is to assist on MVAs while off duty (I agree, TQs and gloves are likely all you need, and maybe a trauma dressing if you are feeling generous), if his department's SOP is to respond directly to a scene before an on duty vehicle arrives (think 80 square mile rural town with one fire station and no in-town ambulance). If a member is closer to the scene, they should have a fully stocked BLS bag, provided they are a credentialled provider and are able to assess and perform interventions until the AHJ vehicles arrive. Could be 2 minutes, could be 20. OP might be first to a cardiac arrest, so he would need to do compressions, ventilate, suction, and provide update to the responding crew for 5-10 minutes until additional help arrives. Or he might arrive at a little old lady who fell and fractured her hip, so all he is able to do is hold her hand until the ambulance arrives. two completely different use cases.