I wanted to emphasize that he flipped on his bike still attached to his bike.
Let's think this through. Would it have been a nice day if he flipped, but came loose from his bike?
No, flipping your bike means you're going to have a very bad day whether you're attached to it or not.
The thing we should learn from your story isn't that clipless pedals are bad or dangerous, it's that you shouldn't run your bike into things.