Possibly another bug here.
I already did the Vitamin Quest for the Dwarves. I tried to do the Driller Quest, but um... you have to "coerce" one of the vendors forcefully.
After he has been disposed of, it says I failed the Vitamin Quest, but I already succeeded in it before he um... got disposed of!
That said, so, where is my Driller boss? I feel guilty and not sure what is the right path here as both paths give items. Ahh too many choices!
[edit] never mind, I found the option.