Perhaps the bigger story here is the progression of Herge's handling of non-European races in his work, from early TIN-TIN IN THE AMERICAS to later more rounded (well, okay, slightly less racist) characters... CONGO (1929?) sounds like it fits into this narrative. As such, it'd be great material for a provocative 20th century pop culture/history unit...
The New Yorker did an interesting article about Herge's life journey a few years back, on his 100th birthday... but I can't find the article on their site at the moment!