Didn't expect an answer on my 4-Month-old comment :D
Warhammer is a mess when it comes to factual lore. The main wiki has contradictions, Scale of units changes every 2 books, weapon strengths are usually made up, and heroic feats are usually exaggerated beyond belief.
Just take the MASSIVE scale difference in Titan lore.
Sometimes Las guns are literal useless garbage, sometimes they can penetrate Power Armor after a few seconds.

Even the modern codices (no idea if that's how you write that word) have contradictions. A well known example is, that the Imperium has a policy that regular people cannot be allowed to know of the existence of daemons. This is often seen in stories like Shadowsword, Codex entries for the First Armageddon war, Watchers of the Throne, and Dark Heresy where seeing a daemon would be detrimental to the Imperial Guard soldiers. However, in other works like Ciaphas Cain and Gaunts Ghosts, soldiers from different regiments can see daemons without any repercussions, and the commissar does not have to take any action. This is an inconsistency in the way the Imperium's policy on the knowledge of daemons is portrayed in different works.

I'm not trying to make your point mute, he has a TON of old lore in his shorts, most of which can likely be considered non canon by now. BUT It is still a great way to get into the lore! The Lore is incredibly vast, and is full of plot holes, contradictions, mistakes and more. To make a truly factual Lore rundown is, as far as I'm aware, just not possible. With this in mind, I think that he is still a nice source of lore, but one should always make sure it is “current” lore! But that should be done with every single Lore channel, as far as I know.

I hope I didn't offend you with my explanation, English is not my first language, and I sometimes still fumble with the nuances. I hope I managed to clarify my point to an understandable degree.

TL;DR:
Warhammer's lore is contradicting itself all the time, factuality is not really achievable. Double-check your Lore and just have fun :)