The primary purpose of notifying ATC of the impending emergency descent so they can clear the way for you and advise of the MORCA in the area and direction of the descent. I've had one in the good old 727 years ago. ATC provided me with a heading to avoid traffic and possible obstructions that would prevent descent to below 15,000'.
TXP to TA??? bonus points. However with the ambient noise, I doubt we would have heard any TA's let alone any RA's
.