That's lowkey actually kinda funny. He got their dad a whole fuckin bottle of sake on obon so now his ghost is stumbling around doing poltergeist activity in a drunken haze. The horror-ish part is the knowledge that the dead do indeed return.
Somehow, I didn't read it as an abusive alcoholic dad, just that the older son had a strained relationship with his father, and the comment about reeking of alcohol being the same as their dad was simply a reference to how the guy soaked the grave with sake. "You can drink all you want" just came off to me as that the dad was an alcoholic trying to limit how much he imbibed. Not ideal, but also not the worst.
The ambiguity of the ghost story and the misleading panels is actually making me a bit apprehensive -- is there something big about Yuta and his family that we've misunderstood? Were we given the worst assumptions because of our limited perspective?