I think we are severely underestimating the computational complexity of animal brains by looking at short-term reactions and snap judgements, not deep thinking or long-term learning. Axons transmit electrical signals and that's what Bostrom is taking to be an "op." But they also transmit vesicles of mRNA and proteins directly from the cytoplasm of one neuron into another, which is an "op" of unimaginable complexity compared to a neuron simply firing (or any CPU instruction), and we have no clue what that means for cognition.