If this was the same situation as he'd previously experienced, Kushina was probably trapped wherever this person had been previously - and if not, then Kakashi couldn't let this person out of his sight. However, when he thought about it their physicality was setting him entirely on edge, but... he couldn't sense anything else except Kushina's typical scent and a near palpable air of uncertainty. Somehow - call it a hunch - Kakashi couldn't see this person with any negative intentions.

"So do I," he continued as he caught up to the strangers stumbling gait (nothing like Kushina's usual bounding strides). "We can go together, and you can tell me who you are on the way."