Perhaps Man Niu is indeed hiding something, but Gu Chengyu is no longer interested in it.
First, Man Niu truly does not know who the Young Master is, nor does he know where the Young Master is currently.
Second, Man Niu knows very little about the members of those organizations, only having contact with the Map Master, while the names of others are indistinguishable.
Third, Man Niu doesn't know the whereabouts of those people either; they all complete their tasks independently without contact with each other.
The most important information now is these three points; since Man Niu is unaware, any other information is irrelevant to Gu Chengyu.
What Man Niu can hide is limited; perhaps it's related to his personal affairs, leaving these matters for the court to worry about!
Regarding those people shrinking back and refusing to show themselves, Gu Chengyu has already thought of another method.
