Lu Xuan had his reasons as well.
Making ancestral graves of any clan into a place for developing and fostering the dead was something deemed absolutely unforgivable anywhere and in any era. One could even say that doing so would ensure that both parties became sworn enemies.
There was hardly any problem if he wanted to take out his indignation and anguish on them.
Be it in modern society or ancient times, making someone else's ancestral grave into a place for keeping undead is something that could easily cause a war.
The guilty party was sure to be hunted down by renowned, righteous clans and sects.
Despite the likes of the Maoshan Sect being a cultivation force specializing in keeping undead, they too dared not do something deemed so sacrilegious.