I think they mean the “superheavy” (somehow a more stupid name than starship) booster rocket is the most powerful. I’m pretty sure by thrust metrics it is. It’s just that the superheavy-starship system can’t put much up in LEO because the starship is huge and heavy on its own.

If you put an expendable second stage on top of the superheavy booster instead of a starship it could put a lot more up to LEO.