In more then one instance the thief opened the package at their house. So its fair to say he knows where they live too. Also, very clear HD video of their faces and vehicles. And there is no way all the glitter is going to get cleaned up - so more evidence of who they are. And home security cameras with more images of them. Not to say these idiots are smart enough to let things be at this point - but if they do retaliate, there is a very high chance they would be caught.
As for your comments about liability. Yeah, that sounds entirely plausible.