Storing waste in place is also hardly any risk. Are terrorists going to retrieve one of these [1], weaponize it, and then deploy it? If they have this capability, then they almost certainly have the capability of shooting up a mall. And the latter would cause more damage. I see effectively zero additional danger presented by nuclear waste in this regard.
1. https://en.m.wikipedia.org/wiki/Dry_cask_storage#/media/File...