Now that I'm over my emotional reaction to his death, I'm not surprised that he may have written porn. Many old time SF & F authors wrote them to help pay the rent, put food on the table, etc back before SF & F sold well enough to pay the bills.
Glen Cook's first book (which he no longer has a copy of) was a porn called The Swap Academy and he's often claimed that he wasn't alone in writing porn - just alone in publicly admitting he done so. In an recent interview (you can find it at
http://jonathanstrahan.podbean.com/e/episode-264-glen-cook-and-steven-erikson/ ) he again mentioned that lots of writers dashed off those for a quick payday back in 60s and 70s.