Influence
Tulnas had told all the ladies in his Guild about Skullius' issue, the curse, informing them that they were not to help him with anything, as this would incur on them, certain death.
Presumably.
Fortunately for Tulnas, even though not all his Guild members were his lovers, they still regarded him very highly above other men and they would usually approach them with caution, their opinions of them much lower because of Tulnas' standard.
For this particular mission, he had instructed, Gertreld, Natalika and Ginie to not, under any circumstances, help Skullius even if he was in a dire situation.
He would be handling that part as his 'friends' were a safer bet for such a case.
Even though, he didn't think too highly of this curse that Skullius had offered limited information for to begin with, he still wouldn't endanger his ladies.