Tatara did a pretty poor job even before his stamina went out. Everyone kept saying how he was doing only basic movements and how he was disappearing all the time. The first part is due to his inexperience. The second part is because he intentionally made Mako shine. The judges didn't realize that he was doing that on purpose. Most of them didn't even realize he was doing it at all. They merely said that they didn't see/remember how he danced. They were victims of a skill a noob has, which sort of makes them less admirable as dance judges.
As for the mom, she even criticized Sengoku for his teaching methods, as well as Tatara's dancing style in a previous episode. That's because she is oblivious about Tatara's motives in dancing as he did, which makes her lack of insight quite understandable. In the end, however, all of them got trolled by Tatara's frame because Mako won. None of them knew that was Tatara's goal, and he achieved it, despite everyone bashing him as unskilled or whatnot.
TLDR: Tatara is a monster (in the making) and none of the judges realized that.