I generally believe a safety getting engaged or disengaged is an issue with the safety and not with the holster, with the understanding there could be the odd sweat shield that is either just awful or magic depending on what it does. I don't know how a holster maker could possibly take into account all the different styles of thumb safeties offered by all the different 1911 makers.
My personal experience with a Colt teardrop thumb safety, with unmolded or even closely fitted deeply molded sweat shields is the condition of the thumb safety is never affected and it merely pushes the sweat shield out of the way.