This is what I think, ever since luffy came back after 2 years the gorosei, cipher pol agents and inu sama was making the move. It could be that the gorosei and the inusama knew that the man who will find what happen to the void century is without a doubt from their point of view is luffy. Heres my reason why, when luffy cameback to marineford after the paramount war, all of that scenes was all reyleigh’s plan just like zoro said, it could be that theres deep message that reyleigh left behind to the gorosei and inu sama on that part, like the ringing of the oxford and reyleigh being there with luffy means the real message on reyleigh plan to go back there is for gorosei and inusama. It could be that just like oden predicted what would happen 20 years on the future the gorosei knew that this would happen.
and reyleigh being with luffy on marineford means that his message going back to marineford is that reyleigh bet that its luffy for sure the one who will find the onepiece, he didnt just did this because his angry or mad to whitebeard’s death i think he did this because of whitebeard’s last word about the onepiece, kinda like reyleigh is saying to the gorosei and inu sama that whitebeard’s death was not in vain because their efforts on saving luffy and risking their lives is for the better future.