I think an overlooked aspect of Whitebeard's character is his relation with Roger, who revealed to him the significance of the "D" word, wanted to talk to him about the location of the One Piece, knew Ace was Roger's son, the one Roger wanted to find the One Piece, was considered as the closest to one piece after Roger died
Why I bring this point? It's because I believe that after Roger died, Whitebeard worked for creating a balance in the One Piece world controlled by the World government until meeting Roger's successor, who he believed to be Ace
And I think that in Whitebeard's head, Ace's life was more significant because they were waiting for the one, who after finding the one piece and finding out the secrets of the Void century, would challenge the world government and free the world of their tyranny, basically his final speech in MF
In Oden's flashback, he always talked about how no country was free(except Wano at the time) due to World Government reign, and thus this was the reason imo that Whitebeard was ready to challenge the world to save Ace's life especially since his days were already numbered due to his sickness
In Ode's case however, not only he was already dead, but it's been mentioned that they only knew it years later, when exactly is unknown, but it's possible that they only knew it when Whitebeard was already past his prime, weakened by sickness, and thus Whitebeard priviledging the final mission of the guardian of One Piece(closest to one piece), grooming Roger's successor, as the one not only to take revenge on Wano, but saving the entire world at the same time, rather than going blindly for a single revenge years later, where even while succeeding could put his future aims at risks
Basically I think Whitebeard simply might have had some time inconvenience, might have looked at the bigger picture of guarding and saving the entire world through Roger's successor than wasting an opportunity for saving a single nation for the sake of revenge
Waiting for the viz translation, but I think it's probably the way Oda envisioned it