Did a statement from a global terrorism organization claiming the killing and demands get made? No....in your example I could grow a beard to ungodly lengths rename myself dress in a robe perform the same actions and it would be termed terrorism. Not every act of murder is terrorism. Again terrorism is global changing like a public beheading with a statement broadcast or a homicide bomber with a group claiming and then making demands. The media has cheapened the term to such an exitent any whacko is now an act of terrorism including some in here.
Only 14 percent of the 45,000 terrorist attacks since 1998 were followed by a credible claim of responsibility. Your’s is the most narrow definition of terrorism I’ve ever heard.
If you dressed up like a jihadi and killed people you’d just be nuts. This guy WAS a jihadi and nuts to boot, so that makes it terrorism.