If Oda wanted, he had all the chances in the world:
- Shamrock could have stayed, he had the standing to be the villain --> Oda sent him away;
- he could have sent someone when the HK explicitly called for help --> two bozos came.
Not to mention, in big arcs the main villain Is always deeply rooted in the background of the arc, as Loki is.
Loki also has the power we know Is the most dangerous to whole Erbaf (screams countdown), he thinks he Is Nika and we know there are two visions of Nika: one destoryer (Loki, clearly wrong), one liberation (clearly Luffy):
Idk why part of the fandom managed to have this big auto-gaslighting ZKK style about Loki not being the villain/adversary of this arc when It has been clear from literally day one: