When did his first scene imply that he is a Akainu fanboy ? He was talking casually with Fujitora and seemed to have an independent personality and a womanizer and rather easy going. He was more like his movie inspiration.
The Aramaki that showed up in Wano is nothing like that. Instead we got a Nazi who is gay for Akainu.
His first scene didn't imply he was an Akainu fanboy because he had all of 2 lines
It's hard to gauge a character in their first appearance and it also depends on the situation
Greenbull had a cushy job guarding the Reverie. No danger, no extra work, no nonsense
Vs the world now being in turmoil due to Kaido and BM's defeat, the Revos invading Mariejois, etc
Stress can change a person
The Aokiji we saw riding a bike on the ocean and commenting on the size of Nami's breast doesn't seem like the same Aokiji that's willing to fight till the death to stop Akainu from leading the Marines
It doesn't come across as a retcon to me