I'm going to be unfair here - there is a limit to how much specificity one can expect in a brief quote but: In what sense is the difficulty "mathematical in essence", and just how ignorant of how much mathematics are the physiologists in question? Consider a problem where the exact solution of the model equations turns out to be an elliptic integral - but where the practically relevant range is adequately represented by a piecewise linear approximation, or by a handful of terms in a power series. Would ignorance of the elliptic integral be a fatal flaw here?