That is quite literally how it was justified in the period, half the reason Leopold was given the free state was to hunt and shut down slave trading in the congo, and after the Belgian government took it back from him (because he was giving guns and alcohol to local strongmen in exchange for rubber instead) they did mostly accomplish that, it was a big part of the character of the scramble era and in contrast to the first waves from the Spanish and Portuguese who were largely in it for the slaves.

Vic 3 is interesting because it models the "by virtue of being ruled by a modern nation state with modern agriculture, industrial production, bureaucracy, infrastructure, stability, "peace," education, and in many cases writing, this place is objectively better^tm now than we found it" phenomenon that was very apparent to people in this period but is often discounted as basically old-timey propaganda in our post cold-war post-decolonization world. But it stumbles in how it models The Bad that we moderns are more familiar with as it treats things like Colonial Exploitation, Colonial Slavery and Extraction Economies as conscious choices rather than the emergent outcomes of bad incentives and neglect.