This is where consistency comes into play
I´m not WB.
I am saying this behavior is consistent with WB´s characterization and the events of the past.
Whatever i feel personally about it is something else entirely.
At the same time, i have mentioned this before, it might sound like a silly excuse to some, but WB was someone who considered his role in the world, meaning hm doing something that creates chaos in the New World would have ended in far more deaths than the suffering of Wa No citizens.
He held the reins of the New World and ensured peace for two decades, two Yonkou going at it, evne if he wins, has big repercussions.
That´s also why Marineford was so big, WG was risking chaos in the New World, WB put Ace´s life above that.
Is it ok? I do not think so.
@ShinmenTakezo has put up in a nice way regarding this....hope this helps for your "understanding"