I think, that I like many other people, am sceptical about the likelihood of a cyclist falling off his bike at a junction (or roundabout in this case) with sufficient force to suffer a fatal head injury. Maybe I'm just being cynical, but we all read about cases of hit and run and we all assume that this situation could easily be just that.
You don't have to make contact with someone to make them fall off.
As for nitpicking over language, I think I just imagine how I would like to report an accident if I knew all the circumstances.
For example, "hit by a left-turning lorry", should mostly be described as "crushed by a left turning lorry" if we really want to convey what actually happens in most of these cases. For some reason, there is a sanitisation of terminaology in news reports about road accidents. You don't see this in other reports, people are still stabbed, shot etc. in other walks of life.