Yeah, I'm not even convinced they'd pick Risacher over Sheppard or Castle if all three are available, much less trade up to get him.
Atlanta is in a bad spot. There's a weird disadvantage in getting the #1 in this draft with their needs. My feeling is Risacher is still a screen, or rather bait, trying to get a trade, but that they'll pivot to Clingan. Clingan just gives their team much more shape, is a great dump-target, solidifies their defense. I don't know what Risacher does for them. They already have forwards.