If they cut it in the wrong place, there's no way for them to attach it back onto the bag when they are done, so you won't be getting the body of the lock back.

You will have replacement shackles and no lock.

If they are kind enough to toss it in the bag for you, that's a different story, but unless you attach the body to the bag too, if they don't cut it where they are supposed to cut it, and put it back on knowing they can cut it and relock it, you are not going to have anything to put the new shackle on.

The lock is a great idea, but given the way they cut tsa locks and toss them, I don't have hopes this will be a much better track record.