I don't understand Law's way of thinking. There are two options:
A - Law wants DD not to give up his status and end up fighting Kaido.
If that was the case he would have simply kept CC and made no effort to contact Doflamingo. This way he's actually giving him a choice, but that's counterproductive if he just wanted him to fight Kaido; after all DD could choose to give up the title and flee, which anyway is the most logical solution: if he chose to stay a Shichibukai he would have to say goodbye to SAD and to confront the strongest creature of the world. So He'd be double screwed.
B - Law wants DD to give up his status and end up fighting the Admirals.He made such an effort to capture CC and to stop the SAD production… and all that just so that DD stops being a Shichibukai? That's ridiculous, that way he'd have to give CC back (unless he's lying, which could very well be), the SAD would keep being produced and the alliance would have no advantage over Kaido whatsoever.
So why is Law doing this at all??? The best course of action would've been to just keep CC, hoping to never cross paths with DD. Also the lying stuff doesn't really seem to fit well with Law, and especially with Luffy and Co., so after all it seems just a dumb move alltogether...
There is also option C:
Law actually wants Doflamingo to get off his self-assured ass and become the pirate he was before. Perhaps Law actually admired Doflamingo but later realised that his idol was taking the situation for granted. Like Moria and Crocodile, he was becoming too comfrotable and set in his ways. Maybe Law wants the pirate Doflamingo back instead of the businessman
of course Law could also be Donquixote's Sancho, waking up the Man from Dressrosa from his dream, to reality. In a way Doflamingo has been in delusion like his namesake, thinking himself to be in control of the new era and a machhiavellian mastermind who can afford to speak flippantly of dreams and justice. But in actuality he's the one being left beind in his delusions as everyone else, like Law and the Supernovas, have caught up and are now surpassing and threatening his power. Now he's awake to the real new era.