But the argument should be showing an agent that does in fact pass these tests. You can't just assert that "this one failed, but surely there must be some agent that is perfect, therefore you can't generalize".
That's not my argument. My argument isn't "surely there must be some agent that is perfect", my argument is this test study can't speak for all agents.
But no test can. They ran an experiment, they got this result. You can run more experiments if you want.
I didn't say any test could. I'm pointing out the flaw in the commenters in this thread generalizing the findings.
The "sufficiently smart compiler" debate, 50 years later :-p