$4 million in 1968 dollars ain't exactly chump change!
I also recall from the documentary that the speed and flare angle he picked were chosen carefully to put the rear fuselage down in the water first and give the drag from the water enough of a chance to slow her down. This was to prevent the engines dragging the front of the fuselage underwater on contact, risking possible breakup.
You may consider his decision-making regarding an alternate deadstick airfield landing on the pessimistic side, but as you say, it all came out OK in the end.