I’ve tried that single-handed decock thing and it isn’t easy keeping your palm on the grip safety and decocking with the thumb at the same time.
I’ve heard of folks losing grip of the hammer, then having thumb damage after it lights off. Thankfully I wasn’t one of them. The Army hammered that into me.
If I recall (I lost my last 1911 in a canoeing accident), when you pull the hammer all the way back, it contacts the top of the grip safety, so you can decock it with one hand. It’s dangerous though, because any slip and it’s going to fire, probably not where you want it to.