I believe that's his point; I read that section not as "please make these instructions constant-time" and more as "please document whether these instructions ar

I believe that's his point; I read that section not as "please make these instructions constant-time" and more as "please document whether these instructions are constant-time, so that we can rely on them being constant-time". If an instruction is constant time but then a new chipset comes out with early-exit semantics for multiplication, everything previously compiled for that architecture is suddenly vulnerable to timing attacks when it wasn't previously. He's just looking for a commitment for the leak and timing semantics of various instructions, even if the commitment is "you cannot rely upon this being constant-time".