You can't be arrested for suspicion alone, and bump keys aren't illegal according to California statute, and I didn't find anything about local statues either. So unless they have a warrant out for them, those people are going to walk free. (IANAL)
Also... cars don't use pins, so they wouldn't have been using a bump key for a car, but possibly a jiggler or a blank for impressioning.
I'd really like to see the evidence for this. As I mentioned in another comment, from what I've read, possession of lockpicking tools are legal virtually everywhere in the USA, as long as one is not intending to commit a crime with them.
It says it right there on the site! Did you read it??
"Illinois infers from the possession of a key designed for lock bumping an intent to commit a felony." Mississippi says a concealed pick set is prima facie evidence of intent. Similar for Ohio, Nevada, and Virginia. Tennessee code might actually make them illegal outright.
Depending on how saavy the local police are, you may get more attention then yoi want if the cops look close enough at your keys.