Like others, I'm not sure what Apoo is trying to gain as fair as "spoils" are concerned unless he's talking about the Poneglyph?? Or just the "glory" of sweeping in to kick everyone else when they're down and worn from war??
Anyway though, like I said before, Drake seems very smart and I don't think he will actually go for an alliance especially considering how difficult it was to gain the favor of some of the SHs who were against him. There is also the fact that Koby painted Luffy as someone who is within reach when close and out of reach when you aren't a friend. He never forgets who his friends are and will basically go pretty far for them. What's more is that Drake knows that the Strawhats (plus Law) have done some crazy things before like liberating Dressrosa by toppling Doflamingo.
Luffy himself also pretty much immediately accepted him so it's like, if he's the kind of guy I think he is, I don't think he'll spit into he face of Luffy by allying with Apoo whose been allied to Kaido for a while.