I think they're saying that while it doesn't matter, the agent and human "do not actutally know" that it does not matter.
Philosophy sometimes says that knowledge is a "justified true belief"*; in this experiment, agents and humans have incorrectly justified a false belief that some applicants are better for certain roles.
* other times, it says this isn't good enough
Seems quite odd to cite all of philosophy as saying something, as if it were a single person with contradictory beliefs..
And then its like you are both saying the justification is incorrect and the belief is false, so its not really like the bare nuance of the concept is adding to the point. Why feel the need to appeal to an (imaginary) authority at all in this case?
"Oh well if philosophy said it, I better be taking this seriously!"