Yes, if we consider Kaidou's point of view as objective, then Saint Shanks is regarded by WSC at a higher powerlevel than Mihawk. This is a significant point that favors Saint Shanks over Mihawk in powerlevel debate, since it directly counters Mihawk's WSS title.
But then again, why give Mihawk the WSS title in the first place if Oda really want the reader's perspective to favor Saint Shanks as a stronger fighter. Imo this is what Oda really wants anyway, to hype every top tiers without a clear-cut distinction. Oda won't rank them definitively, there wont be official ranking, there would just be interpretations while Oda just want Saint Shanks fandom to gain as many followers as Mihawk fandom since it will benefit him as the author.
I prefer Saint Shanks' easy-to-approach character over Mihawk's robot-coldness, but i also can't stand Saint Shanks wearing rags as his outfit. I favor Saint Shanks CoC at Moby Dick, and Kaidou seeing Saint Shanks shadow and not Mihawk's, over Mihawk's WSS title and people's hyping strongest slash in the world.
I also favor Saint Shanks' effortless magma parry against angry Akainu and even making the admiral breaking a cold sweat legit linearts of frightened expression by preaching about fate, as the foreshadowings of an even higher power, than what Mihawk's titanic iceberg cut represents, but i can't stand powerlevel-wise how easy it was for Oda to rip Saint Shanks' arm off, like why did it even if he wanted to make Saint Shanks' a rival of Mihawk's since manga beginning in the first place.