Shueisha including GT in their timeline doesn't make it canon, that timeline which CBR and screenrant is citing doesn't mean anything since its just outlining the timeline of events in the DB animes. Its just a timeline, there was no official statement associated with it and those articles are just clickbaiting people into reading a half assed article that doesn't even show the timeline in question. It literally separates DB and DBZ as separate stories when thats anime only.