re-implementing an algorithm that runs on meat, so it runs on silicon instead, amounted to a 'minor detail of underlying platform'. I live i this one, however.

I had assumed we were talking about low-level emulation: the program explicitly models each neuron, and probably at a lower level than that. And physical simulation is a well understood problem and my impression is that the chemists are pretty good at it.

Trying to do some clever white-box reimplementation of the algorithm I agree is probably intractable or worse. The emulation will be very far from the optimal implementation of the mind-program in question.