Am I right to read this as "the classical computer and quantum computer compete at the task of being that particular quantum computer?" Scott Aaronson is probably preparing to denounce this experiment already.
Not really "that particular", but more like performing a trick explicitly designed to be feasible even for low-qubit quantum computers but unfeasible even for very powerful conventional computers attempting to emulate quantum computing.
Performing such a trick demonstrates that you have a working device that can perform arbitrary quantum computations - unlike, say, the much hyped D-wave quantum annealing device.
If you'd checked the article, you would see that actually he's solidly in favor.
But yes, it's basically "represent a quantum computer of this size", which we legitimately can't do classically beyond a certain size. It's not hugely useful but it's legitimate quantum supremacy, if it works.
Performing such a trick demonstrates that you have a working device that can perform arbitrary quantum computations - unlike, say, the much hyped D-wave quantum annealing device.