Somewhat unknowingly, Di Tou had come across one of the most useful aspects of Spiritual Sense, the ability to "see" and sense your surroundings in situations where the five main senses were obstructed.
As for why it wasn't mentioned in the jade…
Well, while it was one of the best usages for Spiritual Sense, it was also one that came almost exclusively with the territory of Nascent Soul.
After all, most people's Spiritual Senses are so weak that they're scared to let it outside of their body unless they're in a safe controlled environment where they feel safe.
As for wantonly letting out their Spiritual Sense to detect their surroundings… that might as well be asking for a concussion.
At most, in a dire situation, someone who could already use their Spiritual Sense would only send out a small strand to probe the space directly in front of them.
