Here’s why between Gaban and Shiki, it would obviously be Gaban:
On narrative reasons I can agree, but hints are hints:
- the person speaking to Crocus had the same colours as Shiki and had the same hat as the mysterious person here in Erbaf;
- last chapter Oda took back, out of the blue, the exaclty same animals we had seen in strong world (and I mean same, even same scars);
- now we see this man seems to have incredibly long hair (like Shiki, Gaban always had shorter hair) and a goatee (?) that Shiki had and Gaban never had.
Now, It could still be Gaban and maybe It could even have more sense, but objectively there are a lot of hints for Shiki.