"But at the same time this kid is 18. He's young and stupid, who cares? Stupid kid does stupid things and is dumb enough to get caught."
Perhaps though if it was you or me (at that age) or any teenager off the street, it's not national "news." Many people grow up to regret youthful indiscretions, and fortunately most of those acts didn't become national headlines that follow one forever. (I'm just not a fan of every act in this digital age being preserved on the internet in perpetuity. A prime example are those parasitic websites that scrape arrest records to then extort those who have been arrested (whether or not eventually found innocent at trial or charges dismissed)).
If a person has a pending charge and pick up a new one unrelated to the first, unless there is some procedural or legal conflict, the two cases can be (and often are) combined for judicial expediency as it will be the same judge and prosecutor (and public defender if that applies) on both cases. Also, sometimes one jury can hear both charges, and sometimes they need to be tried separately, and that can depend on a variety of factors.