Sect Leader Yao has been stationed on Qingbo Island the whole time, but that doesn't mean he is ignorant of the overall situation.
He too holds a map in his hands, and as Sect Leader, there are times when he must take up the mantle of command.
After all, the situation on the ground is ever-changing, and the information received by those outside of the battlefield isn't necessarily complete.
However, what constitutes a "necessary moment" is up to his own judgment.
The map is a mosaic of colors and rapid advances. The red of the Zhouliu Sect is being lost piece by piece, squeezed around Qingbo Island, which is exactly at the position that demarcates the North-South Line initially.
In other words, they are down to their core territory.