Why the Marines kept Cobra instead of adopting Apache

Why did the US Marine Corps operate Cobra rather than simply adopting the Army's Apache?

Cobra was already adapted for saltwater shipboard service and shared useful commonality with the Huey; navalizing Apache would add cost and complexity.

Sustained operation from amphibious ships requires protection against salt water, so adopting an army helicopter creates additional engineering work. Cobra also offered useful commonality with the Huey family and its production and support arrangements. Navalizing Apache was technically possible, but added cost reduced the attraction of a common Army and Marine aircraft. A Sea Apache proposal and later British maritime use illustrate that possibility. The subsequent question about replacing attack helicopters with drones introduces a separate problem: keeping the aircraft useful when its command link is jammed.