This is my interpretation as well. Also weird to think about publication bias in this way: "these studies about the effectiveness of snake oil as a drug weren't

This is my interpretation as well. Also weird to think about publication bias in this way: "these studies about the effectiveness of snake oil as a drug weren't published, so we must be overestimating how effective drugs are". The authors do mention that there is likely to be heterogeneity in (real) effect sizes, but somehow still go with this title/abstract. Maybe there is a valid conclusion that some of the many nudge studies are probably claiming effects that don't exist. That could be interesting in itself. But rejecting the whole field based on this kind of argument seems wrong.