I'm not describing it as canon at all. It exists in a vacuum, outside of the story. Just like so many other things.
Here's something you can add to that post,
Kamiya pointing out the nature of how the game cannot be viewed as a linear narrative:
Remember, BIO2 was made in a very short timeframe. There were things that were included but cut for various reasons (a scene with Leon/Claire mistaking the Tyrant for human was cut because it was more effective for the horror to just have it round a corner and attack your character with a sudden music queue). There were also things that couldn't be included due to time and budget issues, just like the first game. On top of this, there's the standard common sense in fiction that you don't need to see or read something from a direct perspective to know something happens off-page or off-camera. Games have the added caveat of things happening even if not seen while playing.
BIO3 is the first game to have a "completed" narrative but it still uses player choice and as a result there are various ways to view the story. Archives doesn't present a canon outline of the story. They are just overviews of the story that choose specific events because that's the only way to present the story without being confusing. BIO3's overview outright states in a postscript that it may conflict with the player's experience. Unlike the rest of the book, which is information taken directly from CAPCOM's planning and scenario documents, those story overviews are original content written by the Archives staff.
Official story overviews do not go into that much detail because of the reasons I've stated many times already.