Oswald's exact state of mind as he made this head turn is something we can only speculate about. But, I don't think he was just looking at that reporter with the mic. If he was only looking at him, I think he would have snapped his head around to him fast.
I realize that it's slowed down, but Oswald seems to be taking in, looking at, everything as he turns left. It's not just a quick snap to his left.
Oswald seems to be "looking" really looking throughout, including at Ruby.
That is not the look of a guy who is just on his way to somewhere else visually. That is a pierced look, and it's not at the reporter.