A complex dynamic system has a large number of working parts, and responds in specific ways to inputs and stressors. It just doesn't make sense to think of death itself as a "complex system." They are certainly related- I think death could be seen as an event that irreversibly dismantles a complex system in some way, such that the parts no longer function together as a system.

I was thinking of systems more as just processes that have low-entropy behavior, i.e. those that are predictable in some meaningful way. If one takes the process of death, which is really a behavior of any low-entropy system, to be its own object, I do think that object would be a system under my definition. I agree that yours does not come to the same conclusion, and perhaps my definition of system is too broad.