The reason for showing him urinate naked outside of the place he was staying the night, (Its not his front door. he doesn't have a front door. He is a hedge knight and doesn't own a house) is because the episode is about Dunk realizing that his idyllic image of Arlen was wrong. He wasn't a bad guy, but he was basically a homeless vagabond and acted like one. Dunk understanding that and wanting to do something better is the point.