When I did a defensive pistol course we were taught to slightly rotate the pistol when shooting with one hand. It was explained that it was a more natural position for the hand / wrist. Thats not to say it was completly sideways but I could see where there could be benefits to it.
The wrist locks more naturally if it is canted slightly inboard and recoil control is enhanced. (Like between 11:00 and 12:00 for a right handed shooter vs perfectly 12:00, not parallel with the horizon like this article.
If you are shooting fast and one handed, like in a life/death situation, it is likely close and getting multiple hits quickly was more important than hitting exactly where you sights were looking. It was for shooting at bad breath distances though.