I think so. I can't imagine Shanks being held in reserve for so long only for him to use ACOC coating.
Secondly, the story has consistently put Shanks in a more favorable light than Mihawk, which requires some justification considering the latters WSS title.
Also, the chapter was good, but it got soiled for me knowing all the years long built up hype around Tou has basically led to him ending his career on such a half baked war where the tactics he provided barely even fit the definition of the word.