As the law stands in Texas, the state has no burden, no chance of being responsible for an ND, no chance of being responsible for theft of a firearm, and no need to have a small army of lawyers to defend the inevitable lawsuits. Passing a law as you suggest in the red text moves a significant burden of responsibility to the legislative body, plus all the logistical burdens as well (trained person to handle firearms in emergency, secure room in case of ND, etc., etc etc.)
And, of course, ALL of that crap must be carried by _us_, the taxpayer.
No thanks. Your gun, your responsibility. Get a secure lockbox for you own vehicle, one that is sufficiently theftproof to anything less than a blowtorch, and secure your own gun in your own car. Or don't bring your gun to a courtroom.
Having said all that, I think such a law (as you highlight in red) should be enforced on businesses that put up 30.06 signs. Now THAT would help make a lot of 30.06 signs disappear in a jiffy
