While he is not the most scientifically-minded of people, he has a sufficient grasp of basic physics to know that the door did not fly off its hinges and hit him independent of human agency, but rather that the blow to his face was causally connected to your precipitous exit from the ladies’ room.
Every now and then, we can screw up and not say anything, and everyone can pretend that whatever we did never happened, and it’s better for all concerned. You can, for example, usually get away with pretending that the silent-but-deadly that’s poisoning the air of the conference room didn’t come from you. Everyone wants to pretend it didn’t happen, not just the offender.
But if you have HIT SOMEONE IN THE FACE WITH A DOOR, you cannot pretend it didn’t happen, or that it wasn’t your fault.
So writes Miss Conduct to a lady who hit Miss Conduct’s friend with a door.