This means that there's still a possibility for a truce!
Or rather, the fact that the other side presented this wraith army but hasn't taken action clearly suggests they're expecting him to negotiate.
Obviously, they're wary of the chieftain!
This is one of the few good pieces of news for the High Priest at present.
"Unfortunately, the chieftain cannot intervene carelessly at this moment. Otherwise, killing this young man directly would inevitably resolve our current crisis!"
The High Priest assumed that once the Necromancer died, his wraith army should naturally dissipate.
Regardless of whether his conjecture can stand, even if it could, their chieftain is currently unable to intervene carelessly.
Moreover, now they are inside their tribe.
If they fail to kill Dean McKenzie in one strike, the consequences could be troublesome!
No one wants a violent confrontation within their own home.