I don't know why "age cheating" is treated as such a big deal around here. Pretending to be younger than you are is kind of like having 40+ scoring friend help you with your practice MCAT. Sure, you'll rock your practice test, but that won't help when you show up for the real thing. Likewise, an age cheat might do great in some junior races, but that won't matter when they show up for an actual professional meet.
Its a jerk move to rob a younger runner of a victory or medal because you ran a race you didn't belong in, but ultimately, junior running is all about preparing for the next level, and age cheating won't help with that. Mostly, cheating to win as a junior is just a pointless endeavor.