I'd have to agree. Most ZA BBSs only popped up after 1990.

http://bbs.hmvh.net/lists/the_list.htm

There were a few that were around during the late 80s, so it's plausible that there may have been BBS catering to porn. But to sell it via BBS during the late 80s? From Krugersdorp? No ways.

The people who were really in the know about stuff like this were guys like tKC from The Phrozen Crew, and in his own words, he only started catching onto BBS in 1991.

http://defacto2.net/wayback/the-life-and-legend-of-tkc-2000-...

Phrozen Crew were a very well-known cracking group during the 90s.

https://en.wikipedia.org/wiki/List_of_warez_groups#Phrozen_C...