For the Celestial Sect of Wonders' disciples, they had the Ying Sea to rely on for protection if Lin Feng and the other top cultivators in the sect went to the Spirit Sea.
While there was a big difference between Lin Feng helming the Ying Sea and someone else controlling the Ying Sea, it wasn't easy to attack the Ying Sea even then.
As the Black Heavenly Treasure Tree's will restored, both the tree and Mount Yujing could conceal in void space even if Lin Feng entered the Spirit Sea. They wouldn't reveal themselves just like what happened the last time Lin Feng entered the Ying Sea.
With these guarantees, Lin Feng wasn't worried at all.
However, this wasn't the same for the rest of the other human sects and powers. If three Vipralopa Stage demons descended on the Divine Lands, the humans would be under great pressure.