So now questions like, "How does one measure the amount of water passing a particular point in a river?" or "Why can you not see the Moon during the day?" are being asked.
Are you suggesting that it is okay for a Sysadmin to lack sufficient knowledge to answer those questions? Or that they are somehow discriminatory? I'm just not sure of your point here. I would be perfectly comfortable asking Sysadmin applicants these questions. (With the caveat that the moon is indeed sometimes visible during the day. That question is dumb. But asking why it's visible most nights is not. Interviewers can be stupid too.)
I'm not claiming they weren't being discriminatory. Maybe they were. But that's weak evidence at best.