Honestly he shouldn't care about changing the canon because by him being there it's already not canon and he's the main character of this world now
well he isn't he MC of the world, he's the MC of his own Story... just like everyone else, Ace story ended when he died, as well as whitebeard, Sabo's story continues as well as Luffys, and the marines, pirates, bounty hunters, an normal people as well... There's a farmer out there in the One Piece, known to all as The Heavenly Farmer
ugh forget about not having an effect on the story he should have fun and do wat he wants for him its a living breathing world not a story(its not the char know wats supposed to happen), plus u really should only worry about that when ur weak since u use the story to get stronger if ur already pretty up there in strength like he is it doesnt matter