Kei acting on his own will would be the first time we've seen something like that, but... I do agree with you.

[ that kei may or may not be a staff member. all they know is that he and bigby had an encounter with weapons last night, after all. ]

We don't know where Kei stands, as a staff member or a non-staff member, so we shouldn't jump to conclusions on that matter — at least, not this early on.