The way I see it. Whatever Dofla is trying to do is none of Fujitora's concern, the admiral will try to protect as many citizens as possible, but he will stay blind to Mingo's action. Thats how I understand this page:
He isn't after the stars, because he doesn't care about Dofla's business, he is just following their initial plan: stopping Law and Luffy's alliance while protecting the citizen, but as he said in this page, he won't try to stop Doflamingo.
I hope Oda will clarify this in the next chapters, but so far, that's the only explanation I have regarding Fujitora's action.