If I'm not mistaken, "Tadokoro-san ch26.5" - two pages, barely drafted - serves no purpose except as an exit door for Kirigaya.
I think the author realized that the character was no darling of the readers, redemption or no redemption, and so he decided that she should gtfo of the manga asap. These 2 pages basically tell us that Kirigaya has become a new girl and found (or will find) a new yuri pairing, and that her story will continue somewhere far away from the pages of Tadokoro-san.
Which is a very good thing if you ask me. Last thing we need is to waste valuable page space in that stupid bully.