I happen to know the Glock weapon very well.
There is no safety on the Glock. In fact, the trigger itself functions as the safety. Hence, when you have a chambered round inside your Glock, treat the trigger like a kill-switch. Dont touch it until you are ready to kill somebody. Also, when carrying concealed, most operational types, I would imagine, prefer an open style holster, with no snaps/locks. This makes for more seamless draw action when the shit hits the fan... This is also a liability. Your enemy also has access to your weapon.
So if you dont have one chambered, you know it. You know when you draw you need to chamber. It is one smooth motion from hip/back, load round, sights on target. If someone takes your weapon, you can focus on disarming the person while they try to figure out why the weapon is not firing.
Also, Jack has kids around. That is scary with a Glock. One slip-up (leaving on the counter when you think someone is not around) and you may end up hating yourself for life.