If your going to make a point. Make it. What makes me think this is a wonderful piece of art? Nothing. Like playing the piano badly(when you are an accomplished musician-Tommy Cooper for instance), it takes talent. Not sure someone is having fun with this litter but its by no Master of Art.
1. It maybe a poor image, poorly executed but at least it's having a pop at something that needs to be done (obviously this is a forum for buying and selling urban art so politics, the history of street art and expression aren't necessarily ideal bed fellows)
2. Banksy pieces do not have a divine right to go untouched, whether something good or bad takes its place that's the street for you.