The clamp in your photo looks like the same clamp that broke loose on my '07 last November leaving 12' of tailpipe still attached at the terminus near the bumper and the front portion of the tailpipe dragging down the road from the area near the junction with the resonator. Although it luckily ended well for me, whenever you're pushing a a long section of tailpipe down the road, it's only pure chance that prevents it from hooking into a crack in the road and acting like a pole vault before folding itself up into the floorboard and taking out brake lines (or lord knows what else) at highway speed.
In other words, my experience suggests it's not a matter of 'if' the tailpipe is going to break where you found the rust, it's a matter of 'when' it's going to break.
I'm glad you noticed the weak spot before it broke and hope all's been well since.
Best of luck!