If the FAA licensing issue was to prove anything, beyond all reasonable doubt, it now proves that they were in this 'scheme' together [dual], does it not.
Not necessarily - I can see an argument for having additional pilots licensed to fly the aircraft, present on a long trip. There are any number of scenarios you can imagine - e.g. TCT gets D&V and the aircraft needs to be moved in a hurry - where a second pilot could be useful.
I'm well aware some of the other pilots mentioned in the list will not have had such a luxury, but if you're committed to a flying circus it seems reasonable insurance to me.