It's just it's imprecise like with the brain can "largely be simulated by an artificial network of neurons" - there may well be more to it. For example a pint of beer interacts differently with those two.

I see the paper as utter twaddle, but I still think the "largely" and "probably" there are reasonable, in the sense that we have not yet actually fully simulated a human brain, and so there exists at least the possibility that we discover something we can't simulate, however small and unlikely we think it is.