I was still thinking about this.
If someone did want to take legal action, wouldn't it be easiest to prove that the fluid doesn't last for 100,000 miles? If the dealership isn't willing to change the fluid, or if Ford is telling Dealerships it isn't needed, doesn't this escalate the issue? Then on top of that it seems pretty common to "cook" the PTU fluid in to black sludge by 30,000-50,000 miles, where the entire PTU fails due to heat?
The solution is pretty simple.