I don't think he should have backed down from that statement completely, but Romney is never afraid to admit that he was wrong and be man about it. He said it with the abortion issue. "I was wrong".
Maybe strategically this is well played. If Obama brings it up, Romney will say "i was wrong and did not intended it that way". What else could be said after that? Not much. And if Obama continues, then Romney should say "Look, Mr. President, sometimes we say things that don't come out right, as you have stated in the past that you believe in redistribution of wealth".