I agree K..enn, in that the driver was an idiot if he deliberately stopped in that location. On the other hand it may have been a break down or some emergency, who knows.
I meant that if there had been a collision then surely the rider can only blame themselves, as they would if the obstacle had been livestock, a fallen tree or whatever. 100%
We all ride with a degree of risk, hopefully reasonable well managed. We know that if things go pear shaped whilst going a little quicker than might be considered prudent, then that is what we, as the rider, signed on for.