This chapter makes yamato staying somewhat better because unlike the previous motive, it has some set up/foreshadowing (Aramaki invading the island, Yamato's DF being the guardian deity, etc). The previous one was "I can't believe Oda wrote this", while now it's "ok it makes sense he wrote this but it's far from his best material".
The thing is Yamato did not get enough character development in Wano. So him joining vs not joining was just a trade-off between pay-off that wasn't earned vs a waste of time. And we got the later in the end. Feels like Rebecca all over again.
(Now to be fair, rereading Dressrosa made me like Rebecca's role in the story a little better, because it turns out it was all about Kyros, not Rebecca, and his arc is pretty damn good. it makes sense Rebecca never fights, because Kyros' arc is about not letting her inherit his violence, and in the end he achieves that. It's just the execution is a bit sloppy since Oda has to spend 50 chapters giving Rebecca random things to do instead. So I wonder if Wano will be better when I reread it in bulk. We'll see).