Eh, canon is overrated. Give me a good story. Plus... the Vulcans were apparently conquered.
I don't think I will be happy if they retcon that the entire Federation was actually conquered by the Klingons for a time before they bounced back and won. But this episode and the promo for next week, seem to contradict each other. Saru looks at the war map and sees the Klingon advance and exclaims that they have won the war but in the promo, the admiral says that only 20% of Federation space is occupied. So maybe the feds are just losing badly and not actually conquered?