Are you seriously going to go the cover-up/"false flag" route on this one? That seems to be the direction you're heading.
Swept under the rug? There's many articles published daily.
Take a look. Don't blame CNN and Fox for moving on to the next Trump/Caitlyn Jenner/Colin Kapernick/Harvey Weinstein story. "News" networks are just for entertainment.
No one knows the motive yet. We may never. Dead men tell no tales. There's a chance that the guy was just insane or maybe he snapped. Maybe it was his medication - the same that cause chronic gambling and collecting. But the investigation is ongoing. Maybe we'll find out something. Maybe we won't.
It's almost definitely not a conspiracy. Consider it a 99.99% change that it isn't a vast conspiracy. If you want to hold on to the hope of that 0.01% chance that it
IS a vast conspiracy that will result in the abolishment of the 2nd amendment, a forcible taking of all firearms by blue-helmeted UN troops, and a total end of the American Experiment... well, more power to you.