I carry a Colt Commander frequently in a Milt Sparks Summer Special or one of a number of similar styles with different leather finishes. These don't have a safety strap, they utilize tight fitting molding of the leather to hold the gun in place. Been doing so since about 1987 when I bought my first Sparks holster at Gunsite when I took a class. Never a problem.

Remember, the 1911 has several "safeties" at play at the same time. Thumb safety. Grip safety. Half cock notch is a safety. Many newer 1911's also have a firing pin lock safety. To get the 1911 to fire requires disengaging all of the safeties the pistol has.