I don't think that was the reason at all. They probably liked to continue the anal sex without the the need for "cleaning up" afterwards............
Well the mucous fistula (the remaining blind pouch segment of the rectum) does produce a thick, mucous plug, ever few days or so. It would seem it would not be that attractive. I do not know that for a fact. However the report given at the seminar was that these people liked the penile-colostomy sex. (someone once said it was getting a little on the side.)