Can someone younger play during the Super Bowl halftime show?

You have to have an established band/performer at center stage of a Superbowl half-time show.  That means a band with well known, radio friendly hits.  It also means a group that has had some longevity.  So, any band that meets those requirements might be considered "old".  In my mind, that means the singers that were popular when I was in college or before then and that was when Kurt Cobain was still alive.  Additionally, you need to take into account that the Superbowl is now an international broadcast.  Bands that are well known only in North America won't hold the attention of viewers overseas.  On the other hand, performers who are equally known across the globe or are from outside the US generate the NFL's assertion that the Superbowl is the "biggest party on earth". 

Radiohead may be a great band, but how many top 40 hits do they have?  Bruce Springsteen has had 18.  You may not like your favorite band having to adhere to this criteria to merit being the main half-time show attraction, but it is something that the NFL considers.  

Also, the NFL is run by old white guys, so if they haven't heard of a band, then their chances of going on are greatly diminished.