Respectfully, what I’m describing is not discrimination in the hiring sense. Discrimination is unfair treatment related to immutable characteristics about a person such as race, age, gender, etc.

You could just as easily argue that people “discriminate” against candidates by making them do leetcode, when leetcode is unrelated to performance at the job. Leetcode is a performance some people look at during interviews, just like how you socially meld in an interview is a performance people look at during interviews.

Maybe the person you interviewed was on the autistic spectrum (or had ADHD) and the finger drumming was a form of stimming?

https://en.m.wikipedia.org/wiki/Stimming

I have no idea since I wasn’t there when you interviewed that person but it is something that came to mind.

You’re welcome to disagree with people and present your opposing view, but we just need you to do so without escalating into hostility and personal insults. This site exists to be a place of curious conversation, not a battleground.