a Japanese governmental body purchased a license from Patriot back in 1998 to use what was then called its PSC1000 (aka, ShBoom) processor, might that be a reason the J5, then 4, then 3, then 2 plus an ARM (but no leg, yet) demanded that Patriot be added to the official list of plaintiffs? Might they wish to make the argument that they've already licensed, through the govt body, the patents-in-suit, and therefore should not be getting sued by a co-owner of said patents?

JMHO.