Dancing With the Stars from the outset has been a popularity driven show with viewers "votes" being deciding. Think abou it. Lots of votes means lots of viewers. Not only lots of viewers but demographically sorted viewers. That is a valuable commodity to be sold.

If this were an actual dancing skill competition the public wouldn't have any input. The public doesn't have input to the judging of things like the Olympics, for example. Can't remember for sure but I think other popular participants have been on the show a long time too.

As for keeping Bristol on the show being a "Tea Party Conspiracy"; from the adherents I know that would be tougher than herding cats.

My belief is that there is very little on TV that isn't entertainment or marketing, or both; regardless of what it is labeled. As the saying goes: Follow the Money. The money comes from selling a large viewership to the sponsors. As long as they can do that the show will continue, ad nauseum.