New Orleans had fights among the stevedores; at different times, southern Europeans, Irish, and later Blacks became dominant on the docks.

Why should Smith have known more about the role of black stevedores?
Even in my somewhat later time, Whites in Gulf cities did not associate socially with Blacks and dealt only with those in servant or business jobs.
On the docks the White bosses would have run her off or called the police.
The Black dock workers lived and worked in a segregated environment.
Catfish Row in "Porgy" (the book, not the opera) was fictional, but very close to the truth.