The client told him to cut corners. He acted unprofessionally by not refusing to do so. From an earlier report:

In response to the lawsuit, Gullacher and his companies agreed that they hadn’t done a geotechnical investigation, but insisted that was at the client’s request.

“The RM provided the instruction that no geotechnical investigation should be obtained as the RM was concerned about the additional cost and delay,” says Gullacher and Inertia’s statement of defence.

“Inertia admits that a portion of the bridge collapsed,” the statement says, “but denies that its design or specifications caused the collapse and puts the plaintiff to strict proof thereof.”

Inertia says the RM may bear some blame because it decided to forgo the geotechnical work. It also says that after the bridge was built, the RM “installed gravel on the bridge to a depth of 13 to 16 inches with an average depth of 14 inches, which far exceeded the specified load.”

Both parties share responsibility here. He’s incompetent and unethical and should not be allowed to continue to practice at all. The relevant professional bodies need to issue clear instructions, and strike off any practitioner that just shrugs and does what the client wants. (Yes, it is a problem in my entirely different field too.)