The experiment primarily focused on by the article was carried out on the general population of San Francisco in 1950. At the time San Francisco was 83% non-hispanic White alone. [1] The point of the Tuskegee experiment was to see if untreated syphilis affected blacks differently than whites, as was believed at the time. It was, in part, motivated by a previous experiment in Norway which had withheld treatment for white's suffering from syphilis, which formed the foundation of the modern understanding of syphilis. [2]
If it's unclear, I'm not defending or supporting any of this insanity, but emphasizing that the motivations were in no way racist. In general, if you want to learn more about the selection process for the various sociopathic experiments "we've" carried out through the years, the Wiki on MKUltra provides quite a lot of insight. [3]
[1] - https://en.wikipedia.org/wiki/Demographics_of_San_Francisco
[2] - https://pubmed.ncbi.nlm.nih.gov/28004553/
[3] - https://en.wikipedia.org/wiki/MKUltra#Experiments_on_America...