True, but that seems even more like an issue that would require her attention in that case. I'd love for Vivi to join, but after the events of the reverie and what Imu's up to, the tone just doesn't feel right. She's going through a ton of shit, meanwhile the straw hats are just vibing.
It'd make more sense for her to join at the resolution of all this drama. But in this case, that would be the end of the series. Which is why I struggle to see it happen, as much as I'd want Vivi.