I doubt it's dodgy, the single tube Brompton frame when run over will leave that end result of useful parts. Knowing Brompton prices a new frame might not have been a practical option for the owner.
Someone seems to know altogether too much about what damage is done to a Brompton when it is "run over", is this a confession? Or just another bromptoneer who has experienced the main frame & triangle 'metal fatigue' cracks of death! :-D
Neither, just combined engineering, bike and vehicle knowledge. As someone who is a qualified vehicle mechanic and who has spent some years in the cycle trade as well I've seen enough to assess the likelyhood.