This has nothing to do with fanon. It's nothing to do with "you want it to be true", either. It all comes down to interpretations; perceived differently by players; such knowledge or information is gained from the game become the bases used to draw up conclusions or theories. They don't usually use made up information or fanatises as the bases. Real data(linked with ambiguities) from game gets processed by your brain, regardless of whether you want it to be true or not, and then you maybe end up with personal answers.
I don't think Squall is dead, but his Edea scene has created an another ambiguity. Nothing is specificed or explained for his "wound", so people can interpret however they want.
R=U wasn't made up from made up information and in this case, if everything fits, well you have your answer. I do believe in R=U. Still do and always will.
My expierence/interpretation is set in stone and fullfiled when I finished the game. So, why should I let anything (legal canon) or anybody dictate me? That's just immortal, cheating, waste of expierence and time.
Not fanon.
If whatever Square created in the FF8 game was unintentional (disputable though), then that's thier fault. But it still doesn't give them the moral right to retcon FF8 at a later date just because they're bored or need to make it more interesting for new players.