The top move is where the fun is, I reckon. The rock to the left stops you rocking onto the ledge completely, though didn't try too hard (like you say, would be a shame to ruin the problem).
It looked like it would be much harder without the ledge, but hey, maybe it isn't. Cheers for clearing that up - I really hate ambiguous descriptions and being confused about what the challenge is. Luckily there aren't many in Ru's guide.