We need not understand the detailed operation of a brain to reproduce it functionally on a computing substrate.

We don't necessarily need to understand the detailed operation of a brain to reproduce it functionally on a computing substrate.

We do not mean to include, for example, Horgan’s (1997) hypothesis that scientific progress may soon stop because there will be nothing left to discover that can be discovered, which we find unlikely.

What? Regardless of how likely you think it is, if it did happen, would it be a "disruption"? Would it be a circumstance preventing AI from developing within a century?

above the human level (a human brain running at 1000 times its normal speed).

Arguably not. At minimum emphasize it would have to be a very smart human.