There are a lot of possibilities, most of which are likely to put innocent civilians at a higher risk than is necessary if he knew of the exact nature and source of the threat.
You and a lot of others are committing a counterfactual fallacy - trying to argue the case were circumstances different than they were. The facts are, apparently in this case, that the information was obtained, coconspirators were caught, and the ambush evaporated. The highes skill in war is to defeat the enemies plans, Sun Tzu tells us.
Again, LTC West is not charged with submitting false reports, so one is required to give LTC the benefit of the doubt and presume that the reports submitted were true and that what he is potentially guilty of was what he was charged with and not a lot of other things for which he was not charged.
LTC West was taught the proper skill to defeat the enemies' plans without perfect information. He should have used it.