It was as I had initially figured, an Online only feature.
But the fact that I found that part in the manual, the blueprint map has safehouses marked all over it, what we were shown and told in the gameplay video which was separate from Online, the fact that if you go to those locations you see a Dynasty 8 sign and the garages open etc. etc. all made me believe maybe there is a chance. In addition to the fact that in Online I believe you can only buy apartments and it's an instance because of the nature of Online and how it's set up rather than a physical location on the map itself.
We'll see what happens, I suppose. Friend replied to the ticket asking for further clarification and the support guy did say "houses", businesses aren't houses....but again, probably just a mistake.
We'll see. Will post once he gets a response. If he gets one...
Maybe some of you guys can send tickets, too asking about Dynasty 8 and clarification on residential properties in singleplayer.