Rogue has a lot of experience accepting people as they are. She honestly just considers Oz's wolf a bit like a mutation. He's not, in her opinion, that different from Logan when he got angry. Sure, Logan had more self control when he got angry, but he was still scary and still Logan. Oz is scary and not in control, but he's still Oz underneath the teeth and claws.
Rogue's fear took over and she starts backpedaling. Another step and she starts turn to run away, even if deep inside she knows she doesn't have any hope of running away from the wolf.