I'm not a lawyer but my guess is requiring years of experience isn't discrimination since it would only help, not hurt, the protected class (older workers).
The minimum isn't the important part - they're putting a cap on experience at 12 years which will exclude the vast majority of protected workers, basically anyone who didn't switch careers very late.
The act of "discrimination" per se is fine. In fact, when you select one candidate among many, that's exactly what you're doing. Exercising discrimination. It's just required to be the right kind of discrimination -- based on actual qualifications and perceived capabilities to do the job at hand.
What you are not allowed do is discriminate based on criteria that are not part of essential qualifications for the job. And I for one can't conceive of one single thing that disqualifies, say, Jeff Dean, from holding that job over a candidate a few years his junior.
