If you are a trained fighter it is automatic do get into some sort of defensive stance or to position your body as the situation escalates
That's fine for the firing line, or in classic tv western gun fights, but not in real life SD.
Which I think would involve shooting from lying on your back because you were knocked on your butt at an ATM machine, or setting in a car during a carjacking, or one hand shooting while you trying to push your wife or kids out of the way or behind you.
Wont work when walking around your house at night with a flash light, openning doors, or shooting from cover.
OR setting in you recliner as someone kicks in your front door.
Frankly, I can't think of many SD situations where you can get you good solid
"Defensive Two Handed" stance.
Thinking back on my 20 years in LE and my time with a pistol in combat in SE Asia, I can't think of very few times I could use a good two handed stance. Just don't happen in real life.