Well and it's in response to the editor being like, so, have you accomplished what you wanted to accomplish? And it turns out no, there's one more thing she's been wanting to do, and that's kissing Toda. It's not a chaste kiss, that's why everyone around them is shocked. And it ends with ah! and Mm! because the two of them know each other enough to communicate that way, even if nobody else knows what they communicated.
As far as "why is it suddenly yuri??" like they've been having sexual tension the whole series, which like all of their coworkers have been picking up on forever. And they're both obviously characterized as gay in their backstories. This isnt actually a shocking twist!