Could be…
For reference, Decatur is a small city right outside the city limits of ATL, but inside the interstate perimeter. It’s a very white and affluent area, but a very democratic blue area, too, but quickly becoming unaffordable (my BFF lives nearby and her area is becoming pretty unaffordble). The capitol building is in the heart of downtown, in a more diverse area, and in the past 10-15 years has a lot more people living down there, in part because of the expansion of Georgia State University.
It could be that it’s easier to do such a thing in your own backyard (it looks like this organization is set up more like BLM, with people embracing the name and taking very localized actions). Decatur is filled with lots of well-meaning upper middle class white folks, some of whom are active in politics and some in protesting… But I’m guessing that they also knew that it would be easier to do this than downtown, too.
It just seems to me to some degree that holding it there would be a case of preaching to the choir (or maybe not, as a die-in might ruffle some feathers of the more NIMBY types there), while at the Capitol it might actually bring some attention from local news. My local NPR station does a great job covering local politics, and I imagine if they’d had a die-in at the capitol, they most certainly would have covered it (as it was smack in the middle of the legislative season). The fact that they did not cover it, when they have generally excellent coverage of such protests, suggests to me that it was overlooked, because it was more out of the way, in a place where most people agree with the protesters.
I still think it’s a great idea, though, over all. Hopefully, they’ll stage more protests around here.