The below is from the page:

In contrast to the widely embraced narrative, perpetuated by liberal politicians and the media, that gun violence in America is getting worse all the time, the data reveal that the exact opposite is true.

You said:

the AEI piece focused on WHY NOT has the level of gun violence gone up IF the number of guns in private hands has increased.

They even point out that it's a shaky correlation:

Of course, that significant correlation doesn’t necessarily imply causation, but it’s logical to believe that those two trends are related.

"We know we're playing around with the data here, but come on. It sounds good if you don't think about it!"