Eh, I'll admit that I'm not digging too much deeper into this than just a google search on the number of TVs that are usually tuned in to their games.
I still think all those things you say about SA having deep roots and an international fanbase happened because they got lucky and drafted Duncan and then managed the team really well for decades. I don't think their value predated that enough to justify the NBA intentionally turning them into a powerhouse. They do have Wemby, but if the NBA was funneling him intentionally somewhere that could showcase him, they pretty easily could have sent him to the Rockets or the Mavs. The Spurs obviously shut him down in order to try to pair a good drafted player with him, but that doesn't mean they're going to get it.
So, I think SA is maybe a valuable market because they got lucky, but I don't think they were a valuable enough market without it that the NBA would have bothered enough to influence that luck to make it happen.
And mostly, a lottery conspiracy is just a thing that would have to happen at too many levels with too many people in on it, with too many incentives to make some cash by selling it out. And they don't have to rig the lottery in order to get the product they want on the screen. The legitimate rules already favor that happening.