Liquid nitrogen, people spying on someone's open toolbox in their trunk using CIA telescopic lens just to see what may be inside if it's opened up-c'mon folks. Security is a relative term, one of the more relative ones we can talk of.
As a portable lockbox to temporarily store a handgun (etc.), a bolted-down and locked toolbox is relatively secure, opposed to tossing it under the seat, or even locking it in the glovebox, or laying on the trunk floor and covering it with a jacket. All require large(r) amounts energy and time by someone to gain access to-again relatively being the operative word here.
You could have the most expensive and (relatively) secure portable lockbox in the world, but someone could take your whole car. Is that secure? Of course it isn't, so we might as well keep all firearms in bank vaults and they must never leave....if we want to be as totally secure as we can. But can the bank then be robbed? Yup-another reletive outcome there too.
So we might as well not have firearms at all then I reckon if they can never be totally, foolproof, 100% secure against everyone even including CIA and Mossad operatives. Right?