No, it's really not. The action that put the person in the hospital where they lingered for a month before dying either happened when it was legal to homicide, or not. Without that specific action, the victim would not be dead — or, more specifically, would not be in a situation that led to their death.
Criminal law absolutely recognizes that causal chains have a "first link", without which the rest of the chain wouldn't even have happened. It also specifically subjects the party causal to that first link to special scrutiny.
Criminal law absolutely recognizes that causal chains have a "first link", without which the rest of the chain wouldn't even have happened. It also specifically subjects the party causal to that first link to special scrutiny.