Was it? I just rewatched it couple of times, it seems to me that he was really close and maybe could've fielded it, but stopped in final moment and let it fall down.
I agree with your second section. However, isn't it like @Ethan in Portland suggest? I have no idea who is supposed to do what on kickoffs, but there are two guys in the final line before McKenzie and left one (Gilliam?) is much closer to the ball than McKenzie, he just never looks in the air. Shouldn't he be a good option for catching that? He was literally 3-5 yards from the place where ball touched the ground shortly before that.