Well, lots of folks pointed out what was wrong with cj's analysis. He was confusing the difference of two velocities in one frame of reference with a single velocity in another. In 4d cartesian cordinates, this simply doesn't hold true, as Einstein realized full well.
After some dozens of "tis so", "tis not" exchanges between C.J. Luke and myself, and the passage of about a month of time, I've finally dimly started to realize he probably never will figure out just what his error was, despite vasty effort to make it clear.
But enough gratuitous insults; rather than have all that effort totally wasted, I'll do what every frustrated poster does these days: I'll make it into a web page. This web page. Which has links to
"If seven relativists, with seven blackboards,
explained for half a year,"
do you suppose" the Walrus said
"cj would get it clear?"
"I doubt it." said the Carpenter,
and shed a bitter tear.