I suspect Hinkley was just rejecting, as unhelpful, the deep skepticism of arguments based on pointing out that we cannot prove that anyone else has an inner, subjective mental life like ours.

If that's Hinkley's point, I agree; it seems tendentious to use that position in the process of arguing for or against specific claims about what the mind either is or could never be - but, by the same token, I don't take that 'skepticism of skepticism' as grounds for categorically rejecting ideas like the simulation hypothesis.