Whether or not he was really the Ninth Paragon didn't matter. The Sect Leader of the Vast Expanse School, as well as the other 9-Essences Paragons, had never actually met the Ninth Paragon, so naturally, there were no feelings of friendship between them.
The only reason they needed him was to help with their plan. Furthermore, the most important thing was the Dao eye, which would be of incredible usefulness to them.
That was why they had hoped that the incoming Ninth Paragon would be even stronger in terms of cultivation base.
Now, regardless of whether or not the person they were looking at was Meng Hao or the Ninth Paragon, he had the Dao eye. With that, nothing else really mattered.
If he was the Ninth Paragon, then things were well and good. If he wasn't, then he would have to act like him!
The Sect Leader knew that, and thus he sighed. The other 9-Essences Paragons also knew, and so reacted with mixed feelings.