The Patriarch of the Wuji sect is an advanced-stage Supreme realm expert and his strength was no less than a supreme being, well, atleast in his opinion.
He neither fears the Xianshu sect nor did he care about the authority of Emperor Qin Mo.
This was why he didn't bother to hide his animosity against Lan Ju and his companions. As for the reason, well, it can be guessed by anyone who watched Mark's battles.
In his very first match itself, Mark killed a talented individual from the Wuji sect while representing the Kunlun sect. Throughout the tournament, he also showed his overbearing attitude with everyone from participants to the elders of the sect.
Obviously, he would want to take revenge. But, he cannot act on his own as Mark also had a supreme being as backing. And it's not worth offending such a figure over a disciple who didn't have any personal relationship with him.
Hence, he can only hope for Mark's death within the competition itself.