Tnk probably animated the whole scene, but took massive corrections that completely vanished his style for the cuts at 0:02.9 until 0:11.7 and everything after 0:23, it's just a guess but I'm pretty much confident about it, as this is the climax of the last episode, the likes as Yuuichi Tanaka (who CAD this part) or someone else probably wanted something very model-like.

It's also rather strange to see him going NC in a Tatsuyuki Nagai's show, especially that he'd never previously done it for Railgun until this specific episode, so it's more than likely due to rushed work from him or/and major corrections.