In the United States, this is absolutely not true.
> The Age Discrimination in Employment Act (ADEA) forbids age discrimination against people who are age 40 or older. It does not protect workers under the age of 40, although some states have laws that protect younger workers from age discrimination. It is not illegal for an employer or other covered entity to favor an older worker over a younger one, even if both workers are age 40 or older.
So this might be a good case for some lawyer: this question and email follow up definitely make unreasonable barrier for somebody who finished high school 40+ years ago.
Yeah, it seems pretty discriminatory. As someone with ADHD that was undiagnosed and untreated until after finishing college, I suspect there's also a reasonable case that it's illegal discrimination against people with disabilities.
Being of an older age is not a protected class, so they are able to do this.