On Purpose
It was such an obvious answer that Ryu couldn't believe he hadn't thought of it earlier. Of course the answer would be something hiding in plain sight; it wouldn't even make sense if it was something that was completely out of the blue.
In a way, the reason Sacrum had yet to properly stumble onto the Dao was because there were too many things that could be mistaken for it.
In fact, now that Ryu thought about it, he had had that exact same thought in the past.
Inheritances, Natural Enlightenments, Mortal Endowments… each one of these things was a form of comprehension, and they could easily be mistaken for a Dao under the wrong circumstances. In fact, each one could easily become a Dao should one make it the center of their cultivation.
It was easier to avoid someone when you were hiding where they least expected it, and often where a person would least expect it would be at the very scene of the crime.