The law of conservation of wealth, as it were, would state that the total amount of wealth worldwide (an isolated system) remains constant over time. A consequence of this law is that wealth cannot be created nor destroyed. The only thing that can happen to wealth in a closed system is that it can change form…and ownership.
Continuing from my last post on the integration of econodynamics and thermodynamics, I'll go to the root of the issue and try a more directed response to the OP. From the above quote, I can only gather that the point of this argument is to ultimately provide a theoretical framework for legitimizing economic systems that have built in mechanisms for wealth redistribution (socialism for example).
On this note, we should consider that while wealth can technically (in human-time terms) grow to whatever extent allowed by the expression of human creativity and ingenuity, pragmatically speaking, at any given point in time there is a very finite measure of wealth. And when we measure, while the backwards countries of the world would surely benefit by implementing economic policies that allow for a more free expression of the human factor towards wealth creation, this doesn't change the reality that wealth is indeed concentrated in the hands of the few.
So I guess the point is that zero-sum game applies on two scales with differing circumstances: 1) on a geologic time scale as mentioned in my previous post 2) on an
instantaneous measure of human wealth. Obviously, at any give instant, if a portion of available human wealth were to be transferred to a different group, then the zero-sum principle would apply directly.
Before this ends up sounding like a much ado 'bout nothing, I believe this is where supporters of other non-capitalist economic systems come in to 1) put the blame of this wealth concentration on capitalism 2) suggest systemic alternatives they believe counters this problem. I personally do blame capitalism for wealth concentration, but I'm no socialist or otherwise.
Anyway, I think the poster could have been more clear about this himself, but I think at its heart the question is a moral one, not an economic or perhaps even philosophical one.