The burned man is 100% tied to Shanks
Elbaf is the Shanks arc. We first saw it with Kid vs Shanks on the shores of Elbaf. Now Loki has ties to Shanks. You’d best believe the mysterious man touched by fire is also connected to him.
My guess is it is his brother, and he will probably be the true villain of the arc.
Loki could be villain, but he still needs someone to free him and his crew looks dogshit. Also, his bounty is lower than Luffy’s.
My guess is Loki, being the man Shanks defeated to become yonko, will be Kid’s fight.
Luffy on the other hand needs to get the 4th poneglyph, meaning he needs to fight burned man.