Every decision, on any basis, to differentiate between candidates is discrimination.
Whether it's illegal discrimination is another question (discrimination against people mentioning MENSA membership on applications probably has some measurable differential impact by race or some other protected class, and so could easily, without the evidence necessary to demonstrate business necessity and overcome the presumption of illegality, constitute adverse impact discrimination, but is not otherwise directly prohibited in US employment anti-discrimination law.)
On the other hand, from your description, it does sound a decision that was more self-indulgent than made in faithful service of your employer, which at a minimum is unprofessional in hiring, even if it manages to avoid being illegal.
> it does sound a decision that was more self-indulgent than made in faithful service of your employer
I don’t know about that. A bad culture fit can end up taking a lot of value away from a team. Being self-satisfied enough to join Mensa, and then put it on your CV looks like a big red flag to me.
Whether it's illegal discrimination is another question (discrimination against people mentioning MENSA membership on applications probably has some measurable differential impact by race or some other protected class, and so could easily, without the evidence necessary to demonstrate business necessity and overcome the presumption of illegality, constitute adverse impact discrimination, but is not otherwise directly prohibited in US employment anti-discrimination law.)
On the other hand, from your description, it does sound a decision that was more self-indulgent than made in faithful service of your employer, which at a minimum is unprofessional in hiring, even if it manages to avoid being illegal.