It is true that they are not fact, but I wouldn't call them rumors because they do have a pretty strong basis. Oh and sorry I forgot to include that I'm basing this on The Final Fantasy VII Citadel: Secrets & Mysteries. If you read it through to 'What We Shouldn't Have Seen IV' you'll see that they make some pretty compelling arguments as to why this is true.

So I'll rephrase my question. Why do you think that Aeris' death place was chosen to be the Forgotten Capital and not any other place?