Hi Peter,
Thanks for your kind words and for making the effort to analyze my essay. Yes, I follow your 'discrete' argument. It was your discrete model of plasmas that caused me to take you seriously years ago. But that doesn't apply here. The 'glass wall' is not to be taken seriously; it simply means I want full transparency for all frames. Instead of 'glass walls' on the 'boxcar', we can remove the walls entirely, and frame the argument in terms of a 'flatcar' with no walls. Einstein's inertial reference frame is a mathematical device that does not imply 'enclosed frame'. Ignoring wind pressure, the juggler can juggle on a flatcar as easily as in a boxcar. This removes the c/n argument of your fourth paragraph; it is not relevant to the problem.
As for your mention of 'ultimate' absolute system frame at the center of the universe, it suffers from the same problem as 'distant simultaneity' -- it is not measurable, hence not fact-based. That is why I use 'local absolute' in relativity arguments. I believe the 'local absolute' is always the local gravitational field through which light propagates, and which makes c+v measurable. The local gravity in the station [ignoring earth's rotation] establishes local rest [only perfect at the N and S poles] while the rail car and kiddie car do not generate their own gravity fields and thus are moving through the ether, hence see c+v, not c. This violates Einstein's 'constant c' hypothesis and invalidates his theory, as he said ether would do.
Susskind is very bright, but, like everyone else, fails to see things that haven't been seen for 115 years.
Like Smolin said: "to learn relativity is to experience a transition from one way of mentally organizing the world to another.". Once people change to relativity, they no longer apply commonsensical ideas of reality. That's where the problem lies.
Thanks again for putting effort into understanding my essay.
Edwin Eugene Klingman