The closest Mises came to Strigl’s conception of capital and the subsistence fund is found on page 488 of Human Action (scholar’s edition). Mises is walking through a thought experiment involving a primitive economy with no capital structure or savings–starting from scratch, so to speak:
If these surpluses are merely stored and kept for later consumption, they are simply wealth or, more precisely, a reserve for rainy days and emergencies. They remain outside the orbit of production. They become integrated—economically, not physically—into production activities only when employed as means of subsistence of workers engaged in more time-consuming processes.
Importantly, just before this quote, Mises says that what is saved is a “quantity of consumers’ goods which is needed to satisfy, during the waiting time, all those wants the satisfaction of which they consider more urgent than the increment in well-being expected from the more time-consuming process.” So, yes, humans consume things that sustain them and allow them to produce, but biological needs are just one reason certain goods are valued for certain ends. Focusing just on a reason for consumption is technically outside the purview of economics. Economics works no matter the what the means are or the ends they satisfy. What matters is that we have means and that they satisfy ends to some extent.
A few pages before the previous quote, Mises comments on misinterpretations of Böhm-Bawerk’s subsistence fund:
It is important to stress this point because the term ‘supply of subsistence, available for advances of subsistence,’ as used by Böhm-Bawerk, can easily be misinterpreted. It is certainly one of the tasks of this stock to provide the means for a satisfaction of the bare necessities of life and thus to secure survival. But besides it must be large enough to satisfy, beyond the requirements of necessary maintenance for the waiting time, all those wants and desires which—apart from mere survival—are considered more urgent than the harvesting of the physically more abundant fruits of production processes consuming more time.
One of the implications of viewing consumer goods/the subsistence fund/the wages fund from a purely biological point of view is that production loses its meaning. Means are used to produce means for the sake of producing more means. This is in obvious contradiction to imputation theory and means (no pun intended) that there is no end (both in the timing sense and economic sense of the term) to production. The point of production is consumption, always. Not more production.
Strigl’s thinking, then, only applies to a slave economy. When human labor is applied in production for the sake of sustaining the lives of the human laborers, and not to satisfy more highly ranked ends than the opportunity cost of labor, humans are just owned machines (hence the featured image). Food is the same as fuel, not something a voluntary laborer chooses to spend his money wages on. For Mises, capital cannot be divorced from calculation in a market economy. Without want-satisfaction, the concept of capital, well, cannot be sustained:
The concept of capital cannot be separated from the context of monetary calculation and from the social structure of a market economy in which alone monetary calculation is possible. It is a concept which makes no sense outside the conditions of a market economy.
The idea of capital has no counterpart in the physical universe of tangible things. It is nowhere but in the minds of planning men. It is an element in economic calculation. Capital accounting serves one purpose only. It is designed to make us know how our arrangement of production and consumption acts upon our power to satisfy future wants.