The next sentence says: "Whenever the in-house attacker appears to be making progress, the team responds by adding new distortions to the puzzles." So he is st

The next sentence says: "Whenever the in-house attacker appears to be making progress, the team responds by adding new distortions to the puzzles." So he is still apparently contributing to the difficulty of breaking Recaptcha, even if he never makes enough immediate progress to break it completely.