Yeah but even with Jinbe it made more sense because his crew was about to get Big Mom'd. There's no pressure here for Yamato.
This is just a weird way to end this arc.
Even the FI "not joining" makes more sense, because, at the time, he and his crew were BM's subordinates.
So he had to "leave her crew" first.
Here?
Honestly.....Yamato just became one of the most useless plot characters in the entire One Piece story.
She simply has no reason whatsoever to exist mid raid and don't even leave Wano.