It's interesting going back to the past and then recontextualizing scenes with what you know now. Granted, Oda may not have thought of everything at the time, yet it still fits.
I've always considered this PreTimeskip scene to be misdirection on Law's part. He's reassuring his crew in more ways than one here, soothing their fears about them being left behind in the race for the One Piece. Little do the Heart Pirates know at this point, Law's planning on leaving them behind.
Law was reassuring them knowing full well that the One Piece, that being Pirate King, was not the end goal. Law's goal was to avenge Cora-san and he was fully aware that odds were he could die in the process. It even was an expectation.
Law directly stating that he wasn't expecting to see his crew again on Zou makes that seem pretty damning. I doubt that they would've accepted being left to Zou if they knew these details, so its likely that Law lied to them more than once about the future.
"The rightful place" that Law was aiming for at this point was most likely six feet underground. Not the One Piece.
The first translation I saw for the anime version of that exact scene stated that Law intended to "claim the throne." With the advantage of hindsight, I thought that was reflective of Law's desire to strip Doflamingo's position as King of Dressrosa by any means. Oda was essentially baiting us with the One Piece and becoming Pirate King when that wasn't Law's focus at all, he had other priorities entirely, which is part of why Law was so suspicious when he finally reappeared PostTS. He misdirects people all the time.
To clarify, not that Law wouldn't care about the One Piece and wasn't curious about it, but it's dramatically different from Luffy and Kid who's entire goals revolve around it and becoming the Pirate King.
It's why Law has to solidify that he is in fact pursuing the One Piece now and planning to follow the Road Poneglyphs on Wano. It wasn't what he was aiming for before this, but now he's purposely redirecting his fate. Law literally makes up his mind to go after the One Piece in order to learn more about history in these panels--showing that is what he cares about specifically rather than being Pirate King. He wants to know about the Will of D.
The fact that Oda makes sure to have Law's goals potentially align with Luffy's, even needing to be there as the One Piece is reached to learn the truth about the mystery that has been tied to Law since PreTS during the Post-War Arc when he comments on the D. with considerably more knowledge than any rookie should have.
Then learning he bears it too, that this is a fate that has followed him the entire story? How Oda continually decides to remind us about this in every arc it's relevant with scenes addressing Law? How Law survives despite everything and continually gets saved, reminding the reader so fiercely about Cora-san's realization that something is keeping Law alive. The fact that Bepo is able to save him, that Bepo is seen reacting to Vegapunk's message about the "D." thinking about Lawā¦
Oda's choice to tie Law to the mystery of the Will of D. makes his return seem inevitable in order for us to learn more alongside him.