Honestly, this is just a guess, but I think the color scheme on the cover page is is just the colorist taking a guess that it is Shiki. Thus the same color garment and hair.
It could be, but I just don't see why he, a character we know to be quite bitter in nature, would be friends with his adversarys shipmate. Or why would bring him back to the story now.
I totally agree. The colorist probably just saw it and took a swing. Who knows. Poor artist might just be an intern rushing to get things done for all we know. Or, the colorist could just have been like: "This is a funny reference."
Regarding Shiki, those are all the rational points that I agree with. with the aggressive design elements being the thing that fights them.
To play Devil's Advocate, a thing with Shiki's character is that he respected Roger. He raged over the fact that Roger was going to be executed in the weakest sea. Roger didn't deserve to die
there in his estimation. He called it a humiliation.
He also was perfectly willing to team up with Roger. He refused to believe Roger was beaten. Everything screams respect. Give it years, and nix Strong World, and you have a plausible mellowing with age where he's willing to have a chat with the few people who knew Roger's strength.
We already saw Shiki drinking with Whitebeard, despite their animosity toward each other.
I'd have to use wonky reasoning to justify his return now. I'd have to say that Oda changed his mind about Shiki in the context of the movies not coming into the main manga. I'd have to bring up Shiki being brought back into the story through the Rocks flashback.
Ultimately, it'd come down to Oda making an unprecedented choice. That's really the only way to argue it.
But all that said, it doesn't matter if Redon is hinting dual axes. The only big twist now is if BOTH Shiki and Scopper are there somehow.
Oh! As something I remembered, back in the day, people theorised that the one sitting with Crocus was Brook's old captain who had survived.
