Easier said than done! If they have the freedom to use the stage to do their practice too, it wouldnt work well for all the dancers using it at the same time. So they have to practice it elsewhere and come to the stage ready for the rehearsal just before the real shoot, as the staging people have to work with them regarding the safety measures and requirements. Maybe it was part of the safety measures that they didnt want him to use three wheels, as there would have been a chance of stopping one or two of the 3 wheels from rolling out of the stage if some mishap happens. Even if he had danced with 3 wheels, it would have fit on the stage - no question about it. The question would be how the rolling or controlling of 3 would have been with people in the audience. The stage is far smoother than their practicing floor. So even with the practice, things can go wrong when they have their costume and makeup on, and we have seen that kind of mistakes.
They show videos of practice before each act, though it gets edited out often when they air in the U.S., and if you look at them, you can see the size and structure of the floor. It's flat and doesnt have any highs and lows like the DID stage.
I agree!! 👏