Hmmm... Interesting. Looking at my pictures, I've had this bag since 2006. In all these years I never felt like the cable was actually doing anything, it was just there in case of emergency (as was told). Sounds like the weight of the bag was pulling on the cable for the person writing that review, but I honestly don't know how they had it mounted.
Right now the zipper is coming apart, I've stitched it for now and the screw in the mount is stripped, so I replaced it with a zip tie. I still feel it's safe enough. I'd absolutely hate if my camera fell and broke, but at the same time it's insured and I'd rather enjoy than worry about it too much.

If you think the Cannondale bag will work, go for it.