Lmao, Zoro fanboys don't even know how the world of One Piece works. It's not an Admiral's job to save a Shichibukai. They're 2 different branches of the WG. Fujitora was not "saving" Doflamingo. Fujitora wanted to arrest Straw Hats. Fujitora has nothing to do with Doflamingo. They only made a deal in the palace.
In Sabaody, Kuma literally told Kizaru to f off, because a Shichibukai doesn't answer to Admirals. They only answer to Gorosei.