OK so if the person who uses the building gets his black and gold first, what happens next?
Does the person plot quest trigger and he gets the last black? Or does the owner benefit trigger first and the opponent gets his black and gold?
I don't think that this is in the rules, or the FAQ, but I would:
1. the person who uses the building gets his rogue (black) and gold first
2. then the owner benefit would trigger, giving the owner 1 rogue (black) and a gold
3. The person taking the action would miss out on getting the plot quest extra rogue (black), because none are left.