Something that is bothering me a lot, but doesn't seem to bothering anyone in the media

When the Army Corps of Engineers designed and built the levee system in New Orleans, the staff of the engineering firm who handled the contract claim they warned the Corps that the sheet pilings were not nearly as deep as they needed to be to protect the levees from collapsing in the soft soil, as they did during Katrina. The Corps allegedly refused to listen, and went ahead with the design.

Why on earth didn't the engineering firm come forward and tell the public that they were about to get faultily designed levees?