To my reading, no. That's not the question the study is addressing. The study is examining the climate impact of six soot-injection scenarios, not the premise

To my reading, no. That's not the question the study is addressing. The study is examining the climate impact of six soot-injection scenarios, not the premise of soot injection itself. It cites other papers (some modern, some from the 80s) to justify the six soot-injection scenarios considered, but this study is about applying climate models to those scenarios.