A lot of times reviewers give very helpful suggestion to authors. There are the occasional oddballs who just do not understand and provide idiotic comments but there are relatively rare.
In this case, the reviewer could actually go into the data, since they was open,. Now normally, a reviewer would write something like “The effect of calcium is quite intriguing but does magnesium have any effect at all?
Because the data are open, the reviewer could go into the database and determine for themselves what the effect really was. They were so intrigued that they actually created a graph to send to the authors.
I think this is the first time I have actually read of a reviewer providing data to the authors from the author’s own dataset!