Yan Yu was certainly doing it on purpose.
After returning home, Yan Yu, although he had not scanned the girls' locations, was very aware that they must have been hiding inside the house—the nonchalant demeanor of Xie Ruoxi said it all.
The reason for saying those things was to lure the girls into taking the initiative to strike, which would give him a legitimate reason to assess everyone's true strength.
Why assess everyone?
Because after the trip to drop his sister off at the high-speed train station, on the cab ride to the airport, the girls had engaged in silent, secretive message exchanges for a while.
Even though Yan Yu did not know what they had been discussing behind his back, he could guess it was definitely trash talk about him. If there's something that can't be discussed openly in front of me, why the need for secret message exchanges?
If I say you guys need extra training, then you need extra training. As the team leader, my word is law, and I must follow through!