Grimlock wrote:Totally forgot Gohan's entry. But still, that's something kind of vague. Goku departed in AGE 801, Gohan wrote it in AGE 804, if Gohan saw the explosion, maybe he also assumed they died, as they never came back after that.
It's not really that vague at all. The information comes from a timeline entry, not one of those non-explanation statements (like the supernova maybe being from Goku and Vegeta's battle) or in-story dialogue via an unfolding plot. The entry very bluntly states that Goku's death is what sparked Gohan writing the book. Thus, that is factually what happens since the game can no longer prove otherwise.
You're certainly welcome to assume whatever you like about the how or why of if all, but I don't know if it's worth it if it's just going to complicate what's already stated. Like if you try to twist the entry on Mr. Satan's death to suggest that even though it says he dies, because it doesn't list an actual cause of death, maybe he just faked his demise and took on a new identity to get out of debt or something. Yeah, that works with what is stated, but there's a clear intention to be comprehended.