It is meaningless because he wasted how many years acting the clown instead of waging war against Kaido that could have potentially saved Wano way earlier. The thing that was holding him back was the inevitable casualites of war but as we've seen that was BS in the manga. No soul perished when he fought Kaido. The Yamato and Wanonese shkit later on was a non variable at that time.
Again, thr only reason there were no casualties is because Oden was ambushed with only his scabbards, if he had declared war it would be him+the Yakuza+potentially the daimyos and their armies vs Orochi's armies+the beast pirates right at the flower capital. It would be a blood bath and there was no guarantee that he could win, we saw how Kaido by himself was able to overpower all the daimyos