I think on a character level it was wishful thinking on Griffith’s part. He saw that Charlotte was still enamoured of him when she took that poison dart for him, and he seized on that fact p desperately, but deep down he knew his plan to be king was fucked and he probably wasn’t going to see her again. It’s perfectly consistent with Griffith’s characterization, he fuckin loves his denial.
Plus it tells us that he hasn’t given up. He’s still him. That moment comes right before he saves them all from an explosion by pointing out the thin wall to Pippin, and it works with that to show us that Griffith is still tenacious, still smart and ambitious and sane, and he still wants to be king even if it’s an impossible dream now. And it also sets us up for his later desperation and despair after Wyald makes his helplessness impossible to deny.
On a narrative level it’s v useful foreshadowing.
In no way does it make sense that he was planning the Hawk’s sacrifice lol, he didn’t even have the behelit at that point, even if some people for some reason believe that he knew how it worked and intended to use it.
Like… I’ve seen people take a lot of little character moments like that and twist them into “proof” that Griffith is diabolically planning to make the sacrifice, and none of them ever make sense because the idea that Griffith has been planning to sacrifice them at any point before he says “I sacrifice” undermines the entire emotional thrust of the story.
Plus it contradicts many, many stated facts, like eg you can only sacrifice people you love so much it’s like they’re a part of you, the Godhand’s explanation to Griffith, Griffith prioritizing Guts over his dream several times, Griffith’s confusion when he starts seeing demons and Eclipse references, the fact that the behelit only opens in a moment of pure despair (why would he feel despair if he knew he was about to become a God), the fact that he tried to kill himself immediately prior to the Eclipse, Griffith desperately trying to catch Guts as he falls from the big hand, and Griffith’s clearly explained motivation for making the sacrifice – like the entire sequence leading up to the sacrifice where the Godhand are talking to bb Griffith in his head makes no sense if he’s been planning it all along. How do people manage to ignore that????
Anyway tl;dr that theory’s dumb, hope this helped lol.