I think Gaban hyping Kaido in some way make sense because he thinks the same guy defeated Oden.
Depends who is stronger or weaker, Oden was legit a strong top tier who got defeated by Kaido in a unfair battle. Question is how it would end if both fought fair.
Oden is not weak, im sure he has also a bounty of 2.5B+ and would give any other top tier a good battle. But the place where Oda scale these characters is clear for me.
If Gaban truly tried to stop Loki and failed hard, it just hypes Loki even more but it also open up the question, is there really a huge gap between top tiers? How strong is Loki in comparison to Akainu,Primebeard,EoS Teach or Roger?
Gaban hype and scaling is pretty simple this chapter:
Shanks(for now until we know how he defeated loki)>Loki>(Kaido/Prime Gaban/Prime Oden)?
Feats will tell a lot, if a old Gaban can pull out some crazy feats against Luffy and overall in Elbaf, no one can ignore that he was most likely above Oden too. Like no one will question out if Sanji end up stronger as Yamato or not, because he will!!
Right now there are probably not many characters who are above Loki.
Things will be spicy for the next chapters, this arc will give as a better view for the characters after all.