They didn't left to check up luffy, initially they left to fight kaido (who went down to the life floor and was fighting everyone) after yamato nicely suggested for them to die together lol. and that lead to nowhere bc luffy already got up and grabbed kaido "upstairs" again. Idk Oda uses both Yamato and Momo a lot but it doesn't feel justified to me. Just like Yamato was running after Kazenbo for multiply chapters just for Law kid and bm to take care of it. Yamato didn't even check or commented if Kazenbo is dead. How can you instantly forget about the thing you were chasing for so long?
It feels more like Oda wants for them to be everywhere with no satisfying conclusion rather than move the plot forward more efficiently.