Colt DA revolvers have only one locking point for the cylinder/crane assembly at the rear of the cylinder. S&W and Ruger DA revolvers lock both at the rear of the cylinder and the end of the ejector rod (most S&W's and Ruger Six Series) or on the crane (Ruger GP100, Redhawk, Super Redhawk, SP101, and LCR).
I know that, having had more than a few of each. My point was, what does cylinder rotation have to do with lock up? A Colt could just as easily have a push button cylinder release with a through pin front lock similar to the Smith.
The Colt's clockwise rotation means that the cylinder is rotating the the same direction as the crane's arc when the action is closed
. Put another way, a Colt's cylinder is rotating back into
the frame. The counterclockwise rotation of a S&W or Ruger, on the other hand, is rotating in the same direction as the crane's arc when the action is opened
, so the cylinder is rotating out
of the frame.
Theoretically, the clockwise rotation of the Colt makes it less likely for the cylinder to come open unintentionally under recoil or fast double action shooting and thus it only needs one locking point while counterclockwise guns need two. However, early S&W hand ejectors lacked the forward locking point and I've never heard of their cylinders flopping open when they weren't supposed to, so it may be a non-issue in the real world.