Does a random opinion on an internet forum matter more than that of the physician doing the procedure? You get to dictate the anesthetic (you had one complication which may or may not be prevented by intubation since intubation carries its own risk of aspiration but, hey, its your call). Just the same, the ERCPist gets to dictate his or her part of the procedure, including patient position, regardless whether you or I think it makes a difference.