I will steer clear of any present-day commentary and instead look only at the historical philatelic references:
Specifically, the earliest Scott world-wide catalog I have handy is from 1896:


The numbering system for the envelopes has changed over time, but note the overall comment about the Plimpton series: "The profiles ... are mostly poor, and are wretched imitations of the fine engravings of the Reay issue", AND then near the bottom of the first column, the 10 cent die A is described as "Booby Head" (and the 12 cent die as "Face idiotic. Crooked nose.")
The "Booby Head" description continued for more than 4 decades, through 1939, and the "Face idiotic" description through at least 1949..
So it is not unexpected to find this label in an older collection.
To add a definition from the era, from my grandmother's 1920 Webster's dictionary:
