The general issue here is personal freedoms and our society. Murder should not be illegal. Without illegal murder, no murderers, no getting arrested 22 times for doing something to survive. Pretty sure this guy didn't grow up with parents or neighbors who were great role models.
All that aside, gloating because another human being died is messed up. I don't care who they are, or what sort of life they've led, nobody needs to gloat over their death. Do things happen and people die or get killed sometimes? Yes. Still no need to take pleasure in it. If you can take pleasure or joy in the death of another human being, you're a sick person and would be better off in Nazi Germany or Stalin's Russia.