In addition to the above comments the 40NM is DME to the airport, not track miles. As you say, "Within 40NM/below 10 000' - speed 250" then again at POSUB 6000A / 250", same same, I.E. the notes are not contradicting each other. I seem to remember being vectored from quite far out and then given "direct POSUB". In this case you're back in the STAR but never "passed" the other RNAV points and thus the speed restriction is there again.
CP