Why is intestinal pseudo-obstruction common in patients with lupus?

Can occur, not c'mon. Systemic lupus is a disease that can affect blood vessels, nerves, connective tissue any place in the body. It can be a slowly progressive disease one lives with for many years, to a devastating disease that can aggressively ravage the kidneys, heart, nervous system, joints, lungs...That can shorten ones life to months. If nerves/muscles in the intestine are affected, pseudo-obst may occur, rarely.
Pseudo Obstruction. Chronic intestinal pseudo-obstruction in sle is a life threatening situation that can be reversed by treatment. It may be: (a) a complication or onset feature of the disease; (b) secondary to smooth muscle involvement; (c) associated with ureteral and vesical involvement; (d) the result of intestinal vasculitis.