I'm confused and not trying to be argumentative.
If we are fighting up close and I've got the muzzle in your gut, wouldn't my other hand be tied up with fighting you? And if it is...what exactly is holding the weapon in my hand while you are pushing against it with your body weight? If my thumb is on the slide with enough force to keep it in battery with your body weight against it, it will be hard to pull the trigger.
Two handed grip, sure...I can see it. But I'm having a hard time picturing a scenario that would have me putting a gun in someone's body cavity with a two handed grip while fighting face to face. I don't have large hands, so once I move my thumb it is going to be next to impossible to manipulate the trigger given that there is a hug amount of force pushing in the same direction and only my thumb offering resistance.
Edit:: No, I've been shooting since my pre-teen years and I've never had a grip safety incident that prevented firing. But I've also never been in a life or death struggle while trying to manipulate a handgun.