FWIW, there is a moral argument for shooting this deer.

Male deer butt heads to compete for females. Usually it's just antler on antler, because their antlers match and meet. So both parties usually walk away with just stiff necks. The extra spike on this deer may well mean that he's taking flesh or eyes -- though it's hard to tell where it is from the photo. So shooting him would be good for deer public health. I'll leave it to the rest of Boing Boing's happy mutants to decide if this is worth discouraging innovation in the gene pool.