User blog comment:EmirK/Who do you want for the main antagonist in Toaru Kagaku no Accelerator?/@comment-7719364-20131113004000/@comment-11612775-20131113173437

Hold on! Didn't Misaka remain ignorant of Accelerator's resolve to redeem himself until the Hawai Invasion? That means that hadn't met, or at very least (consciously, as there are quite a few alternative ways in Raildex universe) communicated in any way (aware of each others real identities, like in AC Invasion arc with Touma and Accelerator).

The crossover could only happen in a timeline after that event.

Currently, this arc (presuming the trailer really is for the first arc of the manga side story, and that it really is, as some speculate, during either that arc about Agnese or Accelerator's side of Endymion movie (he had very little screen time and mention), as it's almost 100% certain that it is entirely canon, or something similar) seems waaay too early for that.