Don't worry. I think you can still give him the potion afterwards, just not before the orc war because Korg is the main key to start it.
I see.. The only reason I'm uninstalling is because I've been having other bugs with the game, and when I install after uninstalling the bugs are still there. Only after waiting around a week and reinstalling do they go away. Because don't get me wrong if they went away right after uninstalling I would keep playing because I fucking love this game. Sadly, it doesn't work that way at least from my experience.