In the case of the Remington, the forces that are applied as the ball travels down the barrel push forward on the barrel with a force that is roughly (and maybe exactly) equal to the force applied to the recoil shield. The force stresses the tensile strength of the frame top and bottom as it tries to stretch the frame. So you have force trying to stretch the brass at the top of the frame over the cylinder and the bottom of the frame just above the trigger. Hawg's photo is clear evidence of the force applied to the recoil shield. (Though I truly did not realize that 25 grains would do that after 18 shots)
In a Colt open top revolver, the only member of the revolver upon which this stress can be exerted is the arbor. And more correctly, the mating between the arbor and the frame. So we have a steel rod that is threaded into a brass hole. And all of the force pulls on that rod.
The only force pushing forward on the barrel, if any, is the friction between the ball and the bore. That is certainly not equal, or even close, to the recoil force exerted on the cylinder. And in both designs that recoil force is fully reacted by the recoil shield; the cylinders in both cases are free to move on their respective arbors, constrained only by the recoil shield at the back.
Your thesis omits any mention of moments, which are certainly significant. The recoil force vector is along the centerline of the fired chamber and the bore; this axis is offset from the arbor and necessarily creates a bending moment in the Colt arbor and frame. It's this bending moment that causes the thread loosening in the Colt design. The frame reacts all the moments in the Remington design.