Earth was currently in immense danger, but Lu Xuan had already addressed the problem. Even if he wasn't around, the masters of the Tempest Ocean Realm wouldn't dare to needlessly start any trouble.
The only chance of that ever happening would've been if they were certain that Lu Xuan was dead!
Furthermore, Yun Ling'er and Liu Wanrong were still staying at the Yunxuan Villa. Both of them were masters who had condensed two flowers. Even if they were facing a true Three Flower Realm cultivator, they could still fight back. Since they were both masters who had condensed two flowers, they could still fight back against
They did not lack the power to fight back!
Additionally, Lu Xuan would've left them with enough forms of defense to deal with most dangers that came their way.
With the support of the Earth's defensive barrier that had been spread around the world, defense should not be a problem.