The experiment is literally all about scaling. It tests scaling from distance 3 to 5 to 7. It shows the logical qubit lifetime doubles each time the distance is increased. The sentence you quoted is describing an expectation that this doubling will continue to larger distances, when larger chips are built.

This is the first quantum error correction experiment showing actual improvement as size is increased (without any cheating such as postselection or only running for a single step). It was always believed in theory that bigger codes should have more protection, but there are have been various skeptics over the years saying you'd never actually see these improvements in practice due to the engineering difficulty or due to quantum mechanics breaking down or something.

Make no mistake; much remains to be done. But this experiment is a clear indication of progress. It demonstrates that error correction actually works. It says that quantum computers should be able to solve qubit quality with qubit quantity.

disclaimer: worked on this experiment

Very neat!