The post you are reporting:
One of the other rules of first aid is to not move the patient 'unless it is dangerous to leave them where they are'. This would, I believe, be in line with Vic's point about fire extinguishers. There are a lot of other dangers involved in traffic accidents, such as petrol spillage and other road users, that would also make it imperative to move the victims to a place of safety. Here is the point of Vic's posting about the inherent problems of two door vehicles, especially if children are involved as they normally should be strapped into the back seats. A first aid kit is always a good idea in case there is heavy bleeding which should be staunched, or at least contained, until qualified medical assistance arrives.
Like Bern, this is not something I had given much thought to until I read Vic's postings. Given that, and the different readership of the two main Dover forums, I can see a reason for posting it on both. I am in the camp of those who generally find his posts to be silly or self agrandising but lately most coming from him have been, with a few exceptions, more reasonable or just conversational and I try to take each thread on its own merits.