Is that argument related to saying that animals are p-zombies?
It’s related in that it is intended to set the stage to show that dualism is true, if only for humans—and specifically that it is true only for humans. (In the case of p-zombies, the assertion that p-zombies are conceivable as an actually possible thing is an assertion that dualism is conceivable as an actually possible thing, so it’s no surprise the argument concludes by proving dualism, i.e. something it assumed.)
It’s related in that it is intended to set the stage to show that dualism is true, if only for humans—and specifically that it is true only for humans. (In the case of p-zombies, the assertion that p-zombies are conceivable as an actually possible thing is an assertion that dualism is conceivable as an actually possible thing, so it’s no surprise the argument concludes by proving dualism, i.e. something it assumed.)