I suspect its more likely that the police will assume that your friend in some way antagonised the driver (as all us cyclists do) and therefore instigated his own demise.
At the very least, you can assume this'll be the drivers story. It'll go nowhere I'm afraid, too much subjective view without hard evidence.
Even more unfortunate is that the two things that would have driven to police to take it seriously would have been either injury/death or perhaps some headcam footage.
So clearly you friend is at fault, for not only antagonising the driver but for having the audacity to have survived to tell the tale.