In fact, I think you could argue that the "idiot" in this case was the person crossing the upwind end of the runway, while another aircraft was taking off.
A bit harsh, if that is what you've been asked to do by ATC, you can hardly decide to start orbiting deadside because you hear a take off clearance given, you may easily interfere with something else.
I was given a crosswind join for 20 a few weeks back when I was still between Littlehampton and Worthing and told to report downwind. I wasn't comfortable with that, so reported Worthing descending to circuit height for crosswind join, then as I was approaching crosswind an aircraft was given take off clearance on 20 so I reported my crosswind position. Better that everyone is aware of position I think.