First, my local Dick's was not exactly like the one they picture on the website, it is not open yoked at the top though it does extend long. It appears to be the same one that is on Amazon for $13 but I cannot confirm that, and regardless I wanted it today and was already at Dick's, so I bought their $19 version.
I have a belt sander and grinders, so I opened the outside channel on mine a tiny bit to better fit the profile of the rear bike stay. The rubber insert still fit but more on that in a second. I also ended up grinding a little bit off the stop for the down position so it angles forward just a tad extra for improved stability.
Upside. It fits and it extends enough to keep the bike in a proper upright position, and is definitely sturdier than the Tenfans, though it's not rock solid and we're probably already beyond its outer weight limit with the Rockstar -- it holds the bike up fine, but if I leaned hard on it, I'm certain the leg would snap.
Downside. With only two clamping screws, to keep it solidly in place you have to tighten it enough that the rear mounting plate bends a little around the stay. Of course when you tighten it this much it mashes through the rubber insert and bites into the paint. If you don't tighten it up enough, it's going to work back and forth and eventually wear off even more paint.
In comparison to the Tenfans which if I gave it a 4, this one is maybe a 6 -- nowhere near ideal, but works and is tall enough. We'll see how long this one lasts before I break it -- if I don't break it over the next month, I'll give it a 7.
Best solution would be if Sondors had bothered to weld on a simple, typical 2-hole kickstand tab during manufacture -- c'mon Sondors, you are really this shortsighted?
Hope this helped.