What C-C Fallacy? 5

In running through their three sorts of Tetris play, Clark and Chalmers invoke considerations of something like cognitive equivalence, but they begin the paragraph after that by turning to causal influences:

The kind of case just described is by no means as exotic as it may at first appear.  It is not just the presence of advanced external computing resources which raises the issue, but rather the general tendency of human reasoners to lean heavily on environmental supports. (Clark & Chalmers, 1998, p. 8)

In trying to show that the Tetris case is not exotic, they appeal to humans “leaning” on environmental supports.  This, however, looks like a metaphor for the causal contribution of environmental factors.