Yeah we typically thing age discrimination is saying we only hire people between 20-40y/o but it would also cover it if you said “I won’t hire someone 21 years old only” and still applies to banning someone 21.5 years old. And 21 years and 6 months and 27 days old.

Same applies if I ban anyone with an age divisible by 3. It’s a group of people, but if their age has anything to do with why you aren’t hiring them then I’d say this applies.