For fans of the Dresden Files...help?

I've been reading CHANGES to get myself up to canon before tackling a cross-over big bang idea that's been rattling around in my head lately, but I got to Ch. 37 and hit a bit of a wall...

( Opening paragraph of Ch 37 here )

Am I to believe that Loki doesn't exist in the Dresden'verse? Even though Harry crosses paths with a Valkyrie every other book and met Odin in this one? What? Loki's only the most mentioned character in the Eddas -- it's not like he's not integral to rather large parts of the mythology.

Or am I to think that Harry doesn't believe Loki is real... even though Harry has just had a conference with Odin -- who is stocking up weaponry and soldiers for something... like, I don't know, Ragnarok, maybe? And how does Harry know the story of Thor and Loki's journey to Utgard well enough to reference it, but poorly enough that he mixed up who did what challenge (Thjali, Thor's manservant, lost a race against a thought from their host's mind. Loki lost an eating contest against a disguised wildfire)?

Or is Jim Butcher just messing with his readers?

( Also, a wild theory about Ms. Gard )