The authorities were raked over the coals for being incompetent when, in fact, they had plenty of leads. The fact they kept everything quiet says a lot.
We were led to believe the roommates were sound asleep when one of them actually encountered Kohberger. This guy was actually pretty dumb.
By claiming the two survivors were asleep through the ideal, it temporarily provides
1-safety for these two, because the perp thinks there were no eye witnesses
2-conceals the level of Intel LEOs have on him, relaxing him to make mistakes
My guess
Psychopaths generally are not as smart as they think they are.