"Maybe they don't know it's empty."

That's it, that's all the explanation Shiro has here. It's got his hackles up, metaphorically. It still feels like they're being watched. Like something is circling. Getting closer all the time.

"Or they wanted you to find the offerings. Do they look familiar?"

Then he shakes his head, without taking his eyes off their surroundings. "I still - it still feels like someone's watching us."