There’s no contradiction there. The dominant form of game theory is made for free market capitalism. As I quoted, Amadae acknowledged that game theory can be modified to model other kinds of decision-making.
Even your quotation acknowledges, in effect, that Ostram had to create a new framework, called the “Institutional Analysis and Development framework,” because the dominant, original kinds of game theory lead to the pessimistic interpretation of the tragedy of the commons, with which she disagreed.
I’m aware that mathematical concepts can be modified. That’s actually the solution to Wigner’s so-called mystery of the unreasonable effectiveness of mathematics: only a tiny fraction of the available mathematical frameworks are useful, since the frameworks can be arbitrarily modified in all kinds of useless ways. Imagination rather than data is the source of invention in pure math.
Mind you, judging from the article linked below, Ostram added lots of complexity to game theory, which raises the question whether her framework posits any kind of game at all:
“IAD in-depth field studies embrace complexity to try to understand the key dimensions of each study’s context. When we put them all together, there are too many concepts, variables, global applications, and variations-by-context, to contain in a simple theory.
“The IAD addresses this trade off by offering a language to help organize research, encouraging people to learn it then use it to apply many different theories to explain different parts of the whole picture.
“In other words, it is OK to reject simple models as unrealistic, but to embrace real-world complexity may require a rather complicated language.”