I fear that holding gun owners liable for crimes committed by people who didn't own that gun will only increase crime. When the perpetrator is caught, they"ll lie and say the gun was just sitting out in the open just to get someone else in trouble.
The same strategy is being employed to deal with teen takeovers- punishing the parents in addition to punishing the kids. I believe that strategy will only to lead to more kids committing crimes hoping to get their parents in trouble, as well as less people wanting to have kids.