User blog comment:LittleFlowerKusa/Clone Aging/@comment-24.17.80.234-20120915231552

Let's all also consider that Superboy is a bio-engineered weapon designed to be a weaponized replacement for Superman. If he aged, it would dramatically reduce the lifespan of their "super weapon".

Red Arrow was designed to be exactly like and replace Speedy, without anyone knowing. If he never aged, he wouldn't be able to do that very well, now would he.

The obvious answer to the question is simple, Red Arrow ages because he was designed to, specifically. Superboy's functionality as a weapon is not served in anyway if he ages, therefore, he was designed not to age.