The media does sensationalize what does not need to be sensationalized. If you watch/listen to the original video news link, you'll understand. As for "semi-auto", it was mentioned in the thread as well.
No one's downplaying the seriousness of this kid and the trouble he's in. But to tack on additional drama just because you can shows the uneducated anti-firearm bias, then spreads that view to the masses. And if I know mgdavis (and I do) this is is what his OP was about. To put it into terms for the motorcycle community, that's like you seeing Squids on Gixxers pulling all kinds of crap on public streets and then hearing or feeling the backlash just because you are a motorcycle rider, period.
Many would not buy their kids guns here. I would. I see no problem with my kids owning and using BB/pellet guns or have their own "real gun" (I did, many do). And the calibers that that kid did have is the preferred progression in order to learn handling and technique from younger folk to adults - kinda like starting on a 250 motorcycle and moving up...

Food for thought, just erase for a minute this kid was disturbed and didn't get in trouble. Say he's on par for Valedictorian of his class, team captain, president of student body, dates the head cheerleader, active in his church youth group and goes through middle and high school unscathed. Does it matter now that at random you find out he has the same collection of firearms? After all, he isn't disturbed, angry, troubled, holding a grudge... Or should this guy still "not need" them?
Well, we all don't "need" the toys and hobbies we do have, but we have them.
Let's face it, when someone gets in trouble with the law, one of the first things that is reported is anything that can be used as dirt, is used as dirt. And owning a gun does look like dirt to uneducated, biased anti-firearm community. To the educated and trained, owning more than one gun is no different than owning more than one motorcycle, or stamp collecting, or whatever the hobby is that one is interested in.
It isn't the "ownership" issue that is in direct question here. It is the biased nature against firearms that is so often regurgitated. And that does lead to more restrictions, and tougher ownership laws to abide by for the law abiding citizens that are most often affected by these implementations (bad guys get around laws in place). The story just doesn't end with this kid getting reprimanded for what he got caught for. It does lead to other issues being dredged that does threaten gun ownership. You may not see it, but it's a gateway and opportunity for censorship. This issue may not be in your interest, but it is for others. I see no reason to give up my opportunity to speak for what I see fit.