He did not esteem nor regret because of this. He understood but he did not agree with Guan Longzi. After all, this was his own choice.
Regarding their states, Guan Longzi was definitely above Daoism land immortals. To reach Tian Xianjing, it was not impossible to be done if he wanted to live for another few thousand years. As a matter of fact, it was already very difficult to encounter natural death as his cultivation level already reached the level of a land immortal. This had nothing to do with the strength of power but their abilities to surmount the restraint of mundanity. Even the Book of Life and Death could only use certain special means to induce the deaths of land immortals.
Because Shen Lian had yet to interact with the land immortals of Netherworld, he could only roughly understand from Guan Longzi. He guessed that it could be relevant to the land immortals' three biggest Trials of Dao.